Hey I'm just getting started and I can really only get around 3 fingers in so far... I have a pretty tight pussy. But I really want to be able to fist and I was wondering how other people have started out in the past. Any suggestions?
Welcome.
Patience and relaxation are key. There is no secret trick or technique to speed up the process. Playing often and stretching to or near your limit each time will gradually get your body used to larger objects. Never force anything, that typically results in major soreness or the possibility of injury.