Understanding some basics of sstates helps avoiding some traps. The save game is a memory snapshot and should be seen as such and not a substitute for the normal save.
Save states aren't unstable more than the game was when it was taken, still some rules applies:
1 - Save states does not introduce corruption but can perpetuate existent ones.
When the game is saved normally it saves only the information the code needs to rebuild the actual situation. Those include characters and quests states and anything more the code takes as necessary and that can't be preview in a way to allow creating more specific save states.
When reloaded from the memcard those information enough to rebuild the current situation and position in game are retrieved and everything else redone anew from the disk/image, this grants whatever error introduced before are minimized and corruption like some introduced by wrong patch/cheat may be eliminated.
That's not true for save states since it will reconstruct the memory as it was and so all existent corruption will be there, since they perpetuate corruption new corruptions will just accumulate...
Take one: Create Normal saves whenever possible, mainly between games sessions, and load the new session from it. Still savestates are wonderful and a lifesaver in the between. It's a good practice loading from the memcard and immediately creating a fresh save state, to grant it as clean as possible.
2 - Some stats may rely on the normal save before being effectively commited.
That means skipping some important story change may never have the intermediary states 'logged' into the actual game. Although I don't know cases of that it's still a possibility.
Take two: Create Normal saves whenever possible, mainly between games sessions, and load the new session from it. Still savestates are wonderful and a lifesaver in the between. It's a good practice loading from the memcard and immediately creating a fresh save state, to grant it as clean as possible.
3 - Save states can and probably will be incompatible between different versions of the emulator... that one is already known by most but allows to:
Take three: Create Normal saves whenever possible, mainly between games sessions, and load the new session from it. Still savestates are wonderful and a lifesaver in the between. It's a good practice loading from the memcard and immediately creating a fresh save state, to grant it as clean as possible
There is more to be said about sstates to demystify some assumptions about as good or bad or corrupting it is. But I think those above are enough to show the importance of the "takes" (first thought spelling lessons but it could be misinterpreted).
The save state is a wonderful thing but should be used correctly and never abused. It's unpaired in it's capacity of retaking from a bad step and can be a lifesaver too when playing enough to get to the next save point is impossible or too difficult. But the normal save and normal load step should be redone whenever possible.
It's very important to notice it's not enough just normal save, What really can clean some corrupted state introduced in game for whatever reason is the "normal load", from the most possible clean normal save, try and avoid accumulating corruptions.