#1 ROI is thorough cleaning, decluttering, de-personalizing, and staging as unless you hire it out, costs virtually nothing other than time. Many of us (guilty here) become blind to the clutter in our homes that we overlook as it just becomes the norm, but stands out immediately to buyers. Pare down, most people have extra furniture that should be removed for showings, don't be afraid to leave empty space, have counter tops, desks, tables completely clear or as close to it as possible. Anyone can stage their own home, just google it, it's not rocket surgery, if not you can hire a stager for a consultation appointment for like $200 or a decent realtor will usually handle that.
#2 ROI is curb appeal. It could be argued it's #1 as in a market where inventory is increasing, buyers will absolutely pull up and then not even go inside if the outside does not look appealing, then it doesn't matter what you've done inside. As previously mentioned have the yard in good shape (run sprinklers more frequently to really green up yard, may not be needed in Houston), fresh mulch, flowers in the beds or in potted plants. Shrubs/trees manicured. if there's peeling paint or rotted siding, address it. You mentioned re-staining the front door, definitely do that.
From there it becomes more house specific, based upon what you've said I would prioritize:
1. the fence, not a full replace but either you or you hire out someone to rehab it. reset any poles that may be causing the leaning and re-stain, whether that means power washing or not. Get the gate fixed. A dilapidated fence can give the impression that the whole home is dilapidated or not well maintained, plus it may be one of the last areas a buyer sees, leaving a poor last impression. I doubt this would cost more than ~ $2-3k if you have to hire out, all depending on how big the fence of course, but to a buyer it might look like a $15k problem.
2. I've personally sold 2 houses with w2w hardwood floors and both times we had the floors polished before pictures and listing, I think it makes a big impact for relatively little $ and really highlights a feature of the home and makes it feel more move-in ready. Likewise carpet cleaning is pretty cheap as well, might be worth having them cleaned, unless they are really rough and incapable of getting most stains out from cleaning, no need to replace.
3. you say you have a ton of things on the walls which means you likely need to pare down a lot there, especially any family pictures. too many touch ups can make a wall look worse than no touching up, you might need to plan to repaint an entire wall or room. DIY painting has very high ROI, if you have to hire it out, not so much unless you are in more of a buyers market. Might rely on a realtor or objective 3rd party opinion there.
All of those items really shouldn't cost more than $2-5k depending on how much you DIY, but I would bet return $10-20k in the final sales price if they are left undone, perhaps more if not doing them causes the house to sit on the market longer than it would otherwise.
