Climbing

Well at your level you just need to be learning movements naturally. I.e. keep going climbing. Climb as often as you can while still recovering properly between sessions. My advice for learning basic technique is to watch better climbers climb, ask them to show you how THEY do a boulder that's at the top end of your ability, and try to mimic them. Work on making your V2s feel effortless. Don't just move on and forget a boulder after you top it the first time.

When you DO finish a V3 you're going to be sitting at that grade for probably a lot longer than you sat at V2s, and longer still when you're at V4, so... uh... get used to that is my advice. How quickly you can progress depends a lot on your body composition coming into the sport as well as how often you train (with proper recovery). Stop focusing so much on reaching the next grade, start practicing the basics, and the grades will come naturally. You MIGHT be able to get away with sending the odd juggy V3, but you're never getting anywhere without basic technique, which only comes from a lots of practice.

Edit -- by the way. Usually when people talk about plateauing at a grade... they mean they've been stuck there for years, not weeks. Yes, beginner gains are much faster but a few weeks is nothing, your body is just starting to think about maybe making muscle and tendon adaptations for climbing... with the all-important tendons being much slower to adapt than muscles.