I usually play this tournament and won 1 times and was in money 2 times out of about 15 times I played.

Number of players apx - 30-40

Buyin 10 (casino takes 20% of all the buyins)
Unlimited rebuys in the first four rounds each round is 15 minutes.

You get 2000 in chips and for every rebuy you get 2500 in chips. You are qualified for a rebuy if you have under 2000 in chips.

round : blinds
1: 50-100
2: 100-200
3: 200-400
4: 300-600
5: 500-1000
6: 1000-2000
7: 2000-4000
8: 3000-6000
9: 4000-8000
10: 5000-10000 -- This is the max I have ever been in when I won.

I would like to know what is the best/optimal strategy like when to get lucky and be very aggressive and when to slow-down and play normally and at what stage should you stop rebuying I always stop after or during round 3.

Most of the times I lost is when I am aggressive in round 3 or 4. I push all in with a good strong hand after sensing I have the best hand after the flop or turn and sometimes rarely preflop if it gets to raising and reraising into all in and some one mostly the first, second or third largest chips guy calls and gets lucky leaving me with little chips to play and I don't rebuy afterwards.