Having an active guard
I was training BJJ with a friend some yesterday, who is also a bluebelt but has at least 35lbs on me. It was a fun session, we worked some takedowns and also did some 5 minute grappling rounds. i was never able to tap him during grappling, but i really i was having more success trying always have an active guard. I was always working for an armbar, triangle choke, sweep, or oomaplata. If one didn't work i immediately would bail to something else. Discussing it afterwards he said he was always defending my sub attempts and could not concentrate on passing my guard.
I am really going to try and concentrate on this aspect in the future. At 160lbs i am one of the lighter guys in the class, and fighting guys 190lbs and up is just really tough, regardless of their skill level. I think if i am constantly moving and making them worry about a sweep, submission, or me standing up out of guard i will be able to mount a much better offense against bigger guys. Of course, this requires that i be in much shape than them as well.