On topic: add sorcery points that are reserved for specific usages. Then select usages that aren't particularly min-maxed.
Two quick examples (shooting from the hip here):
* A scroll of a medium power spell that is imbued with a few sorcery points, meaning that it is only when you use the scroll / cast that spell you get to use the points.
* An item (a talisman, say) that provides the Careful Spell metamagic (if the character doesn't already know it) and 3 sorcery points, renewed daily at dawn. The sorcery points must be used on Careful Spell metamagic.
The point is: to increase flexibility rather than raw power. This allows more sorcery points without creating as big of an unbalancing factor as points the player can minmax freely.
That's kind of a nifty idea, I'll be pocketing that for the future.
Myself and a friend started working on a sorcerer homebrew a while back (it fell off because homebrewing an entire class is hard and we weren't exactly flush with free time to do so)
Some of the things we determined for ourselves:
Combining the pool of sorcerery points with a pool of spell points instead of slots felt the best to us. You don't have strict rules for "this magic power is meant for this thing" which felt very much like a natural caster. It also removed the feeling of losing out by creating spell slots or using metamagic (We have both oftn felt frustrated that by using one we limit the other)
However, we did run into some hiccups. If memory served me, at low levels it felt about the right size, but by high levels the pool was massive. He was working on finding the right numbers and progression to feel right to us.
We also wanted (probably around level 5 or so) to give the sorcerer the ability to burn hit dice to create more sorcerery points. Now, this all is predicated on another house rule we both use. HP does not recover to full after a long rest, you spend hit dice just like during a short rest and recover half HD (I allow it to be flexible when you recover that half). This means that for us, using those HD is a big deal, big enough that we even wanted to lower the chances of rolling it and getting 1 pt. I think we were leaning towards rolling and adding con mod, but I'd have to go back over our notes.
I do remember what I wanted the level 20 ability to be. I called it "Power Incarnate" and it allowed the sorcerer to (once per day) refill their entire pool (sorcery points plus spell points). Is it obscenely overpowered... yeah, it is. But for a level 20 "I might get to do this twice in a multi-year campaign" ability, I wanted it to feel epic in scope.
The other big thing was giving them more metamagic options (having only two until level 10 feels bad) but also to create more metamagic options unique to each bloodline. So Dragon sorcerers should have access to a metamagic that allows them to do X while shadow sorcerers should have access to an ability that lets them do R.
Also, we planned on some thematic spells to give them a few more spells known.
I know it can be a lot, but I feel like it is a good direction for the sorcerer. The pool plus metamagic makes it feel like they are forming spells out of thin air, an empowered fireball isn't a fireball spell plus this extra sauce, it is a completely different spell in terms of resources spent, and it might even open up some creative uses for the magical energy.
Additionally, the ability to regain spell points (and potentially far more than the wizard) at the cost of their own health feels thematic. The limit on a sorcerer's power isn't the source of magic, their blood boils with magic, the limit is how much their body can handle before getting overwhelmed.
It feels different than the other casters