Let's see
Well , I am talking regarding the freeroll tournaments , this should be enough to answer all the questions from above .
Usually i am building a nice bank and later on I am loosing everything ...
Also at the begining its a little bit difficult , because everybody is putting All In ..
What king of strategy should I adopt ??
In a freeroll,
Early stages: the Early stages are crucial. People are just pushing right about anything, what these people fail to understand is that the Early stages is where you have the maximum advantage. So the idea in the Early stages is to
play tight. Don't take unnecessary flips. Preserving stacks is much more important, let the gamblers take each other out. Play ABC poker. That said, don't fold premium
hands {TT+, AQs+, AKo} to single opponent. But if it goes multi-way all-in have a range of something like {QQ+} to call. Remember you're not here to gamble and you can't win a tournament in the Early stage, but you can lose one.
Middle stages: Starts around when 1/2 the field is gone and antes have kicked in.
Adjust your bet sizing and your opening range. The goal here is to start incorporating steals in your game. Steal from late position whenever you have a good hand.
Late Stages: Starts around when you get into the money. You should not let go of this opportunity, this is where you could make 1st or you could come 10th.
Add more aggression, add more steals, and also be willing to take flips. When I say flips, hope you understand a KQs in antes can be powerful. So do not miss out on any chance to add to your stack. Know that, this is the stage where you're really okay
gambling.
Final Table: Back to the basics.
Play ABC poker, observe opponents, their tendencies and once you've enough information, implement those in your game.
Play short-handed perfectly, most people make millions of mistake short-handed without even realizing it. A hand like {A9o} which might not be that good to open from UTG+1, becomes a good hand to open from that position.
3-handed:
Make the opponents fight with each other. That means, defend your blind, 3-bet sometimes. Make sure they know that you're there to fight and they're better off picking each other than to pick a fight with you.
Heads-up: I think you should read up about heads-up. Different people have different strategy, but the jest remains the same.
Put a lot of pressure on the opponent.
This is just a simple strategy. You have to work on it, add more details (Stack goals, etc). You'll be able to do it once you have gained some experience playing a particular type of game. Never hesitate to learn, from books, from videos, from people around. And you'll surely improve.
Hope that helps.