Blackjack Tournament Questions

[Kaeser]

Ok so my local cardroom is now offering a $20 blackjack tournament every monday. House adds $100 and takes no rake, right off the bat this seems like a +EV situation. However I'd like some advice on how to maximize my chances.

Structure is 21 players (3 tables of 7) and 21 hands dealt. Start with 100 chips, 5 min no max. 6 deck shoe dealer hits soft 17. No surrender but blackjacks pay 2-1.

Top player at each of the 3 tables as well as the 3 other players with the highest chip totals meet at the final table where they begin with 100 chips. Seems like if you don't beat your table it takes about 180+ to have a real shot at the final table. Payout structure is 50/30/20.

My plan was to play a martinagale strategy starting at 10 chip bets. Min betting once I get a decent chip lead or reach 200 chips. This seems like a fairly risky strategy, but assuming I don't bust it sets me up for having about 170-200 chips after 21 hands. That should put me in good position for final tabling/placing.

I've never played BJ tournaments before so any advice/resources would be greatly appreciated.