First of all, you want to make sure that you single out the reason for which you got banned, for instance GPS spoofing. If you were in New York and accidentally (or not) jumped to Germany, you should open Nox (or other app/phone), set your location to the initial one (in this case, New York) BEFORE opening Pokemon Go, and then open the game, thus being back where you started.
Secondly, walk to a pokestop, spin it and close it. You won’t be getting any rewards from it, however, doing so up to 40 times (or until you finally receive the rewards) will remove your soft ban.