Brand-New, So Humor Me

[JosephAnthony]

Sheridancat you seem like you could give me some useful overall strategy really briefly.
The "tourneys" i play in, example of one:
-8 people buy-in for 5 dollars. 2nd place gets their 5 back, first gets 75. Thus, super top-heavy.
5 dollar buy-in gets you 300 "dollars" in chips, and blinds are 5/10 to start out with.

Last tourney i won, i was heads-up with Franchesco (second-best player there.) He kept giving me fits because we each had about 1200, and blinds were only 20/40 (i told you they rose slowly). Anyways, he kept going all-in before the flop, about 60% of the time. I figured i would bust him out with a big hand, but then he started folding his garbage hands! Even though i had the chip lead, i felt like i was being pushed around.

Last/winning hand:

He finally made a small raise pre-flop (100 fantasy dollars). I called it with J,10 s. The flop came Qs-3h-6s.
I figured i had a good flush draw and a bad straight draw, so i set him all-in, thinking, he'll probably call me, because he is trying to trap me with a pocket pair he had.

He called, and when he flipped, he had Q-10clubs, so all he had was TP. Fourth street was 7s for a flush by moi, so i won.

Was i right to bet this? My figuring was i had about 20% chance of hitting the flush, giving me 4-1 underdog status. However, considering i stood to win 75 dolars if i hit it, and only 5 if i didn't, i somehow concluded to myself that i had 15-1 "pot odds". Is this thinking wrong because it was heads-up? Or because of the silly tournament set-up?

Feedback appreciated.