I think you should play them strongly, but also consider the action at the table, as well as player styles.
How are you playing your hands? do you have any hand histories? What is your betting pattern? Are you miniraising and giving them odds
to call? or are you betting so they don't have the odds to chase that straight? Are you going all in and getting 5 callers?
If you are going all in and getting beat by an odd hand then that is just poker. You are a favorite to win X+% of the time, but they will win X-% of the time. And if you are playing callstations, it can really affect your probability depending on how many live cards there are in the hand.
What you want to achieve is to narrow down the players to a heads up situation where you can dominate and have the best chance to win. But sometimes the callers just call and suckout and there is nothing you can do.
If you find this happening alot, it may be the site you play on. I play on Full tilt alot and you get idiot callstations who will suck you dry, but on Bodog I find they respect the bets alot more. It might also depend on the time of day you play, and also the blinds. Low limit has alot of callstations so I hear.
A standard raise is 3XBB but you can and should vary it. some people do 3-5 times the BB plus 100 per player entered into the pot. So if you have 3 players before you and the blinds are 100, you would raise at least 600. You, of course, will need to feel out the table and adjust your play accordingly. If you have alot of callers who chase till the river and catch, then maybe switch tables.
Don't forget to randomize your play, and remember your positioning. Although you have a strong hand such as AA, if you are in the cut-off you get to see what everyone else does first, and as you know pockets do not gurantee a win. So play JJ QQ KK cautiously and do not be afraid to lay it down when you feel you are beat. I see alot of people call down AK feeling entitled to win just to get beat by a low pair.