i played up until just a bit after pets were released, since then have there been any updates or better guides to making one cause idk if i messed up or not

depends what guide you're reading i suppose ..
what do you want to know specifically ?

best way and how to lvl heal and hp heal pets to get max lvls and stuff

spend money is the best way honestly but that was their intentions when they introduced pets.

https://www.realmeye.com/wiki/pets

Max all skills before fusing pets.
When you fuse pets, your new pet will have the same skills as the 1st pet in the fusion (see guide on fusing pets) and the level of the skills is equal to the average between the 2 pets.
It costs more gold/fame to feed higher rarity pets (hence why it's best to feed them to max before fusing).
1st pet ability is determined by the pet race, other 2 are random.