It took me years to constantly stay at a positive ROI. There is no magic formula. I would suggest a few things for tournaments:
1. Tight is right.
2. Bluff less
3. Learn to "shift gears" and know when its you NEED to loosen up or play tight.
4. Stay ahead of the blinds, take more chances early not later.
5. Learn to be aggressive.
6. Learn to be aggressive with the right hands. This doesn't mean only AA, KK, QQ.
Tournament play is a lot simpler than cash games as they are totally different animals. In lower stakes poker if you play TAG you most likely will be successful. As the stakes go up, the game loosens up. There is more money out there, more chances are taken, and more deception is used.
No matter what you read, youtube, ect... there is no substitute for just playing. The more hands you get in, the more situations you are exposed to. I've been playing poker for 20 years for money and still read every day to learn something new, reinforce good habits, and just stay sharp, but still try to get a few games in every day also.