Ok, I need help. I know one of my weaknesses, is, when being close to the money, (3 handed, top 2 pays or 4 handed, top 3 pays), I lack of agression. It seems I just cannot be agressive enuff. I don't know how I can correct this and I know people take my blinds a little more than they should of.

I'm not stupid enuff in the sense, I will steal blinds too, but only if I get some kind of hand that I'm confortable with. Will bluff, but rarely to steal blinds.

Let's assume all the players left have the same amount of chips.

For example, if I'm BB and get raised, I will fold K-9 to K-Q. K-Q, I might play, depends of the player that raised.

Low pocket pairs, 22-66, I won't raise. 77 and more I will raise.
I need A-8 and more to raise unless I'm shortstack, I will push A-5 and up.

On the flop, what if I don't hit one of my overcards ? Should I still bet strongly if I raised preflop ? That's where I have problems usually...

Can anyone give me advice or a general strategy playing shortended, near to the money situation ?

This is a hard one, there's no hard and fast rule to how you should act. It really depends on the other players on the table and what you've noticed about them so far. At the shorthanded stage you're playing the other players rather than what is in your hand. As for putting in a follow-up bet after you've raised pre-flop I would say you should almost always do that, especially if there is only one other player in the hand. You may not have hit anything but the chances that they have hit anything are fairly remote too. I'd raise and then fold if they reraise - most of the time they will have to fold. It sounds like you are a pretty tight player (like me) and hopefully the other players will have noticed you haven't been playing many hands and you can use this to your advantage at the later stages. If you suddenly start raising and playing strongly they'll have no choice but to assume you've got good hands. I usually build up a tight image and then loosen up when it matters and the blinds become worth stealing.

Watch these two videos:
$27t Win Video