My homebrew is scattered among the public section of this site, but this document will summarize and link all of the relevant documents, list all rule modifications, and describe my philosophy about homebrew.
Generally speaking, all homebrew is subject to changes whenever I feel the need. Actually, the game itself is also subject to those changes - occasionally I find that the there are problems in the rules-as-written that (a) cause problems themselves or (b) stop whole classes of homebrew from working.
All of my homebrew feats (and modifications to book feats) are listed in their current form here. I have made a few other changes to how feats operate that:
Homebrew archetypes can be found here, and homebrew classes here. I reserve the right to weaken any abilities that turn out to be too effective or powerful, so choose based on the concept, not because you see an interaction that you can abuse to be crazy effective.
I dislike the core wildshape rules intensely - most people that want to be a Druid of the Moon do not play the archetype to feel like a bag of hit points, they want to feel like a feral beast. While I'm willing to allow players to use base wildshape, any of my archetypes that involve wildshape assume that we are playing with the revised rules, found here. These rules shift the ability to (a) be more about the form's abilities than its HP, and (b) be simpler, requiring less preparation to use properly (having to bring stats for 20+ beasts to every game is silly).
Polymorph is wildly overpowered for its level, and functions simultaneously as an emergency healing spell, a utility spell, a scouting spell, a combat spell, and a control spell. I've substantially reduced it's effectiveness in a couple of those roles - you can see the details of that change here.
This isn't actually a 'rules' change, but so few DMs play stealth in the way that I do that I feel I should warn players - stealth works like it works in fantasy novels, not like it works in World of Warcraft. In combat, that means that 'hiding' and popping out again in the same location can surprise a thinking enemy maybe once (if it has other things to pay attention to), but not over and over. Out of combat, that means that you can't 'hide' in literally any location, and many rooms don't offer any good place to hide (though the shadows above the door will often work, if you can climb well enough). Some mechanical details are described here.
While the details of Bonus actions and Reactions are very important to managing game balance, I think that having rules about swift actions and free actions is a mistake. I will be interpreting those interactions through narrative, rather than by counting - unsheathing two shortswords at the same time is obviously reasonable, with or without the Dual Wielder fat, for example. Picking something up off the ground with one free hand or picking two things up off the ground with two free hands in the same location are both allowed. In general, I will let you know if you try to do too much in a round - if you are trying to build a character around a behavior that involves fiddling with a lot of swift actions (like a shield magus or something), talk to me and we'll work out a way for that not to matter.
The various abilities like Lucky that allow one to modify a roll after it has happened are not tightly constrained - instead of applying until the results have been announced, you can apply these abilities until some other randomness or behavior is resolved, like the DM revealing information to the players, or a die being rolled and landing in a way the players do not like. (If you roll a second save and succeed, I'm totally fine with returning to before that point and ignoring the result - it's not to your advantage, after all.)
This actually extends further than those abilities - if you perform an action and succeed, I will usually allow you to cancel that action and change your approach. Typically I chalk that up to poor communication about the likely results of actions on my part (in-game, I think of this as your character thinking through the likely results of their action, assuming that they succeed, and then deciding not to follow through on their plan).
I don't use this optional rule, though I do have a post correcting the math of the Unearthed Arcana that describes it here. I may consider using players-roll if I ever need to deal with a 7+ player table again, but it's not necessary with my current 5.
I am changing the way all ranged and melee cantrips scale. Instead of (a) adding more dice or (b) adding more attacks at all of levels 5, 11, and 17, every cantrip (including eldritch blast) adds a second attack at level 5, and adds another die to the first attack at level 11 and the second attack at level 17. Abilities that add your spellcasting ability modifier add it to both attacks/saves. It's slightly more complex to describe, but it allows cantrip damage to scale like melee damage (without feats).
In my largest change to existing archetypes, I'm disallowing Extra Attack for full casters. I'm replacing it with an appropriate ability bonus to cantrip damage, and updating the melee cantrips to scale appropriately - see this post for details. You don't need to care unless you're playing a Valor Bard or Bladesinger (or one of my similar homebrew archetypes), though you may be interested if you use the melee cantrips Greenflame Blade or Booming Blade.
In general, the goal of this is to make it so that casters cannot match the DPR of martial characters with feats, unless they use spells or spell slots to do so (a Bladesinger with Haste on will generally match a Polearm Master without it). The melee cantrips scale as well as Extra Attack (assuming a class feature that adds a modifier to cantrip damage), but don't allow two-weapon fighting, polearm bonus-attack, or other similar boosts.