Hey Wally, best advice I have to you is to keep doing what you're doing. I used to be great at talking to adults when I was a kid - I think the formality made it easy for me - but for many many years, I had difficulties with people my age. This is a learning process, and the best you can do is keep pushing the limits, trying different types of humor, and seeing what works for you. Try watching some comedians you find funny - I always liked Russell Brand (search for him on YouTube).
The more feedback you get, the more you pay attention, the more calibrated you'll become. I'd highly suggest checking out unbreakable, as we get REALLY deep into the nitty-gritty of the rules you're looking for.