A lot of people think of "luck" in poker as making a draw.  For example, if you make your flush draw, you got "lucky".  In fact, you may have been correctly drawing and you simply made your draw.  There's some chance you will and some chance you won't; you can sometimes make good +EV decisions on very unlikely draws.

In fact, the primary way to get lucky is in the hole cards.  One of the best things that can happen to you is to get AA when someone else has KK, because you are a big favorite to win and they are likely to put in all their chips.  Now if you get AA and everyone else has weak hands, you are a big favorite, but will probably just win the blinds, so that's quite unlucky.

In the long run everyone has the same amount of "lucky situations".  Of course you do make your big money on hands that you get "lucky on", and you lose big when you get "unlucky", but those are just the two sides of the random factor in poker, they should average out to good play overall.

One of the keys of poker is to allow yourself to get lucky.  You do this primarily by saving your chips for situations where you have a good chance to double them up.  If you're bleeding off your chips on hands that are likely dominated, you won't have them when you get AA and he gets KK - you want as many chips as possible when those situations come to you.  Another key is to always play aggressively.  By playing aggressively, even when you might not have the best hand, you allow yourself to stay in the pot and perhaps hit a miracle card.  If you play passively or weakly, you will be frequently folding, and you don't give yourself enough chances to hit a great card.