Though it is hard to answer, from your body type you sound like an inside fighter or a really fast/explosive guy. Not that you are, but that would be optimal for the above mentioned frame. I would recomend small steps and a tight defense, when you get in side explode on the first opening you see with hooks and upercuts. Most importantly however would be to remember good technique, protect yourself at all times, and know your opponent.
I my self am 6'4 and 1/2, I wiegh about 215lbs. I am pretty quick for my size and i like to move around and throw jabs and crosses alot. If I see an opening I will unload a combo or maybe one big over hand. However, my long arms keep me from being effective inside so it is always neccesary for me to get a good clinch. If I can control a guys head or arms it makes inside fighting alot easier for me because shorter arms are faster. Holding a good clinch on the back of the neck can definatley add power as well.