Basic Elements of Preparing Your Home Before a Listing Appointment
Before you list your home, & even before your initial listing appointment, it's a good idea to at least get a start on the exterior of your home preparations. With anything in doubt, be sure to ask your listing agent, whether in advance of the listing appointment or at the appointment.

Image courtesy American Real Estate Media at a former listing of mine
This advanced preparation is especially true if aerials or other exterior photos are being done at the 1st appointment & the seasons are changing for the worse in terms of your property's aesthetic appearance. In some cases this concept is true even if your property is changing for the better by season in more rare cases, i.e. being able to see waterfront more clearly when there are no leaves in trees in between your home and a body of water and it's Winter now while you plan to list in the Spring.
Keep in mind the factor of time regarding any preparations for your home. If you only have time to take care of exterior items before a listing appointment, and the season is changing for the worse, focus on exterior items first if your agent will be taking aerials or otherwise arranging aerials, even if it means that your interior will have plenty of to dos at the time of the listing appointment that you're already aware of.
Preparing your list
Before you do anything, make a list of issues that you're already aware of in the exterior and interior. After you've made that list, go through the interior and exterior thoroughly, and see if there are any other issues. Look out for corrosion, such as rust, wood rot, and leaks. Look out for safety hazards, such as exposed wires, soft flooring, & falling hazards.
If you'd like help with your list, a home inspector is one resource, and an agent is another, though the inspector will typically be able to identify more issues than your agent can, and will typically go in places where your agent won't go (i.e. crawlspaces). If you do get a home inspection, and plan to take care of a lot of the items in the inspection, it can actually help your sale if you get the inspector to come back and then produce a new inspection (typically with a reinspection fee of a lower amount than the initial inspection) that you can present to buyers at the time you list, visible to agents on MLS.
DIY or Contractor/Cleaner?
Some home preparations you may be able to do yourself and some items you might have hired out to contractor(s) or cleaner(s). Consider the time you have available, your skill level, your amount of discretionary time, and the value of your time as you determine which is best for which job. I've seen some terrible DIY projects. For instance, just 9 days ago, a seller told me without me even asking that a few DIY projects that her kids had done at her home needed to be removed. At the same home, the seller had laid some tile where I couldn't have told that it was done DIY without her telling me. Her father had been in that industry. I've also seen where a seller was so skilled that he did items better than many contractors would. I've also seen where an owner made sufficient money with his occupation where even things he knew he could do and could take the time to do he decided not to because he could use time more effectively in his career where he made too much money with his career to do much himself.
For instance, when I purchased my first home, I bought a fixer upper. I pocketed solid equity gains in the first year due to renovation and getting it at a discount because it was sold as is with much work needed. Most of the renovations I had hired out to those more skilled in each task than I was who could do them faster and with better precision. I could have painted myself, but it would have been very time consuming to do so, and as a real estate agent without a fixed schedule, the more time I spend with my work, the more money I will acquire. The only jobs I did myself were ones where they appeared to make sense to me. For instance, I saved $450 while getting a work out (& I don't work out enough already, so that was helpful) by removing a stump in my front yard with a pick axe etc. I likely did a more thorough job than the contractors would have done. In terms of cost per hour vs what I made at the time with my work in real estate, it made sense. The contractors I used seemed to raise their prices after the initial large estimate when I asked about adding things, and wanted to charge me $50/window for installing blinds, not including the cost of material. I was able to install the blinds at a rate of 3/hr, and I didn't make $150/hr after taxes etc. at the time, so it made sense not to hire the contractors.
If you do things DIY, consider what tools you have and what tools you can obtain temporarily prior to sale. There are plenty of places that rent out tools & construction vehicles if you need it, and sometimes you can borrow from family or friends. I've even lent out tools to my clients before, though my tools are limited & won't always be available.
Selecting Contractor(s)/Cleaners
Estimates can vary substantially for the same jobs, so it's not a bad idea to get a few if you haven't already found someone you know and trust. In the most extreme example, I've seen where 1 contractor charged $662 while another charged $5000 for the same requested job.
The lower the bid you choose, the higher the probability of problems with the work, all other factors the same, but sometimes you can find someone who does a great job for a reasonable price. It's a good idea to check on things like the contractor being actively licensed, what class they are rated, what their ratings are, etc. before hiring.
Let me know if you'd like my list of contractors for Hampton Roads, where I primarily focus my attention. Whether you're outside of Hampton Roads, or whether you in Hampton Roads but would like additional options to my list, Google Maps is an excellent resource. Here's an example looking for a plumber in the relatively rural area around McKenney:

Image courtesy Google Maps
Inspecting Work
While you would think it goes without saying, it's important to inspect work during the process and after completion. If something doesn't look right, ask the contractor about it, and if it still seems fishy, get a 2nd opinion with a picture or video shown to someone who knows more than you that you trust. In the past week, a property I had under contract with a buyer fell through because whoever did the costly repairs under the house didn't do a good job, requiring much of the work to be redone in order for things to be made right before termite/moisture inspectors, and we had 3 different companies that we sought bids from. In this case, the person who did the job moved out of town after doing the job before the property was listed. If someone has been in the business for a long time in your area, they will tend to have less problems, but that's not always the case. Be aware as well that some excellent companies might not have many reviews if they are not aggressive at seeking out reviews, even if their work is far superior to other companies. For instance, the company that did landscaping for me at my rental for a while didn't have any location I could find to leave them a review, despite the fact that they were fantastic in quality (especially compared to the previous 2 landscapers I hired for my rental) at a great price.
Selling As Is
In most cases, I don't recommend selling as is. There are some exceptions though. I get into that more in this article.
Ask Your Agent
If you have work that you are considering doing to your home that you're not sure about, especially if you don't know whether or not it will be a cost effective repair, it's a good idea to ask your agent about it before engaging in it. You can accomplish that task prior to a listing appointment with photos often.
Checking Your Work Right Before Important Times Starting with Your 1st Listing Appointment
It's important that within 24 hrs of your listing appointment (& any photos that follow, as well as prior to the listing going live, prior to open houses, & ideally prior to each showing or string of showings), you go through and make sure that things were as you left them, since sometimes things can change, and you want to limit the number of issues that your listing agent needs to identify so that you can focus your attention in that meeting on those issues that you don't already know are necessary to take care of.
Consider Storage Space
If you have a lot of items in your yard or interior, consider moving them to somewhere else before listing and before photos. If you have a few trailers in your yard, and you could move them to another property you own, you may want to do so. There are plenty of options for self storage in the area, and in Hampton Roads, American Classic Self Storage is my go to with many locations.
Preparing Your Exterior
To prep your exterior for sale, see my separate article on the subject here.
Preparing Your Interior
To prep your interior for sale, see my separate article on the subject here.
More ideas
For more ideas, here are some resources, including some I used when creating these pages:
How to Prepare Your House For Sale: By Open Door
How to Prepare Your Home for Sale and Attract Buyers: By HomeLight
How To Get Your House Ready To Sell: By Rocket Mortgage