Your position at the table can be vital. Pre-flop, you would like to be the dealer since this allows you to see how many players have called, or have raised, before you decide whether to enter the action. It also means that you have fewer players after you who might raise the betting and force you out of the action. If you are the dealer, or one place to the right of the dealer, in these circumstances, you may consider slipping into the action with weaker hands. These will be shown in Poker Tournaments where your style tends to be freer and more aggressive.

In simple terms, the earlier you are to bet, the stronger you need to be since there is always the possibility that you will be raised and that there will be some callers or even re-raisers. If you make a bet and then, because of raises, you fold your cards (and this will happen reasonably often), you have wasted your initial bet. For that reason, unless you have one of the premium Pairs (AA, KK or QQ) or the “Big Slick” AK - on which you should always raise - in early position, you will be keener simply to call the Big Blind bet and then, if raised subsequently, to call that raise and see the flop.
In mid-position (about halfway between the Big Blind bettor and the dealer) you would loosen up a little bit and, in late-position (the dealer or one seat from the dealer) you might well decide to raise on any of the key 21 hands in an attempt to drive out the Blind bettors and win the pot there and then.

As an example, with a good, but not brilliant hand such as AQ, you might think like this:
You would be unwilling to raise an early position, since there could be stronger hands yet to show themselves and you might well be re-raised. However, if you are on the button (the dealer), or close to him, you might well choose to raise, in the hope of scaring off the Blind bettors and pushing out anyone else who has called on sub-premium hands.