Probably the single biggest tip that changed my training actually came from myself: "Forget what your body type is. Seriously, forget it."
As soon as I stopped thinking: "I'm a whateverthefckiammorph, so I'm skinny and can't gain much muscle or fat and blah blah blah," I started building more muscle and strength (and put on quite a bit of fat in the process, most of which I've now removed and I'm still about 10kg heavier than I was back then), because I allowed myself to build more muscle and strength.