We play alot of T20 cricket and here's my tips:-
1. 20 overs is longer than many people think - don't panic about scoring quickly.
2. Good bowling still requires playing out, treat it like a normal game but still look for the singles.
3. Look for a boundary an over + singles against the weaker bowlers, you don't have to take many risks to post 150+ in 20 overs.
4. As others have said, play to your strengths and back yourself as 20/20 does require calculated risk taking
5. Disagree that openers have to see out the opening bowlers, bat 10 overs or the innings. You have to setup a platform of ideally 5-6 an over for the first 6-8 overs, but if your side is decent you'll have big hitters to come then up the tempo. If your 40-50 off 7/9 overs get on with it!