Hey Elton.
You simply cannot afford to fear anyone in a game of poker. Some people may be aggressive, but are you going to whimper out each time you come up against a challenge?
A couple of things to remember are:
Firstly. These aggressive players are merely human....just like you and I. However, they just play poker to win. This is how you should play. Don't play to limp through to minimum cash play to win the tournament.
Secondly. Take time to have a think about what cards your aggressive opponents have when you come up against them. Also, start considering not just your cards, but also things including position, position, position. Why position? Cos that's far more important than your cards or theirs!
Give it a go!
Good luck
BB