"How do I get stronger?" has been solved and the solution is Starting Strength.

Evidence: The set of my friends who are strong is exactly the set of my friends who do / have done Starting Strength or a close variant. Also, I used to lift with several competitive power lifters (including someone ranked top 100 nationally in the deadlift) and they unanimously advocated it.

These are relatively large N and effect size btw, i.e. I know at least 15 people who've done SS and they're out-benching the non-SS'ers by 20 pounds on the low end, and 100 pounds on the high end (I pick bench because it is the exercise most people are familiar with; the gap for other things like squat is more like 50 pounds on low end, 200 pounds on high end).