The best way to become looser is to work on one concept until you're comfortable with it. At this point, I'd probably start at light 3-betting. Depending on your volume, try to light 3-bet in LP at least 5 times in early tournaments followed by c-bets. Once you start getting comfortable, start using it to against players you have a good read on. The more you do it, the more you're aware of the situation and the more comfortable you'll get.
From there, graduate to floating, apply the concept into your game again, at least 5 times in a tournament and use it more once you get comfortable.
If you're uncomfortable with light 3-betting, you can start at blind steals. What you're aiming for is being put into situations that require a ton of thought so they're more familiar. The more familiar you are with certain situations, the more you'll feel comfortable with them.
Lastly, remember that betting is probably the most powerful tool in your arsenal. It provides the betting lead and it turns the tables from you having to make a tough decision to villain making tough decisions.