Beginner; feel like I get pushed around

Hi all. Well, I have played poker a few times at various get-togethers over the last 10 years or so (I'm 27), but I never really took it seriously. Then, about a month ago or so, one of my friends got a poker set and we decided to play a NL hold 'em 1 table tournament. I thought, "Well, I've watched WPT a few times; I'm in!" And, I got my ass kicked.
So, I started doing a little research on how I could get better. I was (and still am) amazed at how much I didn't (and still don't) know. So, a few weeks ago I started playing online for some experience. Seems my biggest problem is this:
I play a fairly disciplined game before and at the flop, but I used to often end up losing big on all-in or big raise calls. So, I resolved to quit doing that. But, now I feel like people can push me around. I mean, what stops someone from just stealing the pot by going all-in on me?

One more question: here's hand history. Did I make the right decision after the river? Any advice is appreciated...


Paradise Poker No-Limit Hold'em Tourney, Big Blind is t30 (6 handed) converter

CO (t825.00)
Button (t2502.50)
SB (t1515.00)
teddosan (t2060.00)
UTG (t1880.00)
MP (t1217.50)

Preflop: teddosan is BB with 9:spade:, T:club:. SB posts a blind of t30.
UTG folds, MP calls t60, CO calls t60, Button folds, outSB folds, teddosan checks.

Flop: (t210) 8:diamond:, J:diamond:, A:diamond: (3 players)
teddosan bets t80, MP calls t80, CO calls t80.

Turn: (t450) Q:spade: (3 players)
teddosan bets t110, MP calls t110, CO calls t110.

River: (t780) A:heart: (3 players)
teddosan bets t150, MP calls t150, CO raises to t575, teddosan calls t425, MP calls t425.

Final Pot: t2505

Well, if they get in the habit of stealing from you with all-ins, you're only going to lose a few small pots until you get a chance to shove a strong hand down their throat. There's nothing wrong with playing somewhat weakly against a maniac, I think.

As far as the HH, I think there is very little chance that your straight is any good. I'm betting CO filled up aces full of jacks or queens and is hoping a flush pushes on him.

Edit: Hmm, no, it was unraised preflop, so I'm probably wrong there. I suppose he could still have AJ, maybe A8, or possibly he is the guy with the flush.

Fold on the river, you're winning against an ace but losing to a boat, better straight and flush. Not many second best hands want to raise like that into a field of 2 others especially with an uber calling station like MP.

-'rilla

easy call. pot odd lays you 2.5:1 ish. I don't see straight slow playing on 3 diamond flop, C/O will have either Fullhouse/flush but he will just have trip aces often enough to make this call justified.

but what the hell were you thinking on the flop? what did that betting accomplish exactly?

The flop bet was pot building for later stages, and i dissagree that trip aces will pay you off enough. A lot of people scare easily on a coordinated board. If anyone is going to have a naked ace, it's MP. I don't think baby flushes will kill you here but nut flushes and the nut straight on the river will.

-'rilla