problem with short-handed aggressiveness

[Navers]

The other day I played a friendly short-handed home game with three other people. It was a NL game with 5/10 blinds (that's cents, not dollars). My aggressiveness was paying off in the beginning, but as the game progressed I started losing large amounts of money as they started calling my big raises with mediocre cards.
.....For example, I thought UTG was trying to steal, and with A9suited I raised the pot to $1.50 because this was shorthanded and the game was rather loose. I didn't want a cheap flop for anyone and I wanted to cut down their implied odds. They both cold called and the A2o (UTG+1) won with a straight on the flop. , I bet out 50c on the flop and a dollar on the turn since there was a flush draw showing on the board. UTG+1 won by just calling my bets.
.....How should I have played that hand? I think now that my preflop bet was too big and risky, but how can I drive out players? Should I have driven them out with that hand?How much should I have bet to protect my hand and expect a profit with less variance? Also, how tight/loose or passive/aggressive should I be in these loose shorthanded games? Should I wait for premium hands since the postflop bets are significantly larger compared to the blinds and be assured a win? Or should I play medium suited connectors? Any help at all would be appreciated.

[MisterKing]

A few things...

Your concern about the particular hand where you lost 15x the BB with A9 to A2o is something you simply cannot dwell on. Any one hold 'em hand has some kind of shot to beat another PF -- even 67s has about a 25% chance of beating AA heads up. So don't get stuck on a particular bad beat or series of bad beats, though I know this is easy to say and hard to follow.

You said your game was 4-handed. Without getting too far into it, I think its safe to say that A9, suited or not, is an automatic raise in a previously unraised pot from any position. Can't live in fear of AK every hand...

As for your broader strategy questions, your best bet is to read, re-read, and read again the no limit, shorthanded, and poker theory forums here on 2+2. The amount of information available on here continues to blow my mind, and new players like you (and to an extent me as well) should really be thankful that so many more experienced folks offer their thoughts and advice every day for free.

Good cards, and get readin'