[exE36M3]

Also depends on the wheels and what brakes you have... too little of an offset (where the wheel is deep inside the wheel well) will risk having the rim (spokes) hit the brakes or the rim/tire hit the coil, coil/spring perch, or strut/shock.

Personally, I suggest FINDING someone here on the forums with THE wheel/set-up you are looking for and ask them about any issues they've run into. Most people post their Christmas stories when they first get stuff, but rarely post the... "Aw shoot... that sucks" stories.

Rims/wheels are stupidly expensive already and it's hard to backtrack once you buy them and put them on.

In my case, I went with an aggressive 19x9 et 38 rim up front with a 235/40 tire (taller/wider tire).
And now my tire scrapes the fender and wheel under hard compression (even with a roll).
Camber plates works but... they rattle. If I drove like a like a show-car guy, no biggie. But I charge corners and drive pretty aggressively.
If I had to do it again, I'd back off my offset by 5mm.