Important thing is to be patient and wait. Dont lose your courage, when you are with 1300 chips when the first player has 18k or something. He has taken a lot of risks to get to there, which for you is good news, since in mid to late game he must only make one, which will cost him the tournament. You need to play only premium hands and calculate pot odds
, outs when neccessarily. You need to play strong hands because most of the times you enter a pot, it will come to put your whole stack in the middle, which you wouldnt want to do with 2 7 off suit. When you have a real hand you need to be very aggressive. If you get an AA,KK,QQ,AK early you need to be very aggressive. With AK you need to raise a lot, where with the rest of the hands you dont want to slowplay it, but if you want you need to raise by that much that it wouldnt be profitable for people to play hands like 68s and such, because every single hand, that is dealt, someone flops a monster hand. But he cant know that he would have made a Full house with 2 7 for example. Thats why you need to raise when you play, and raise big, so people with not that strong hands dont find it a good spot to pay. Early you need to play premium hands, meaning pocketpairs (limping in that case, if you hit a set raise) AA,AK,KQ (thats not much of a strong hand, but Ive seen that its working pretty good for me. I didnt play it at the beginning, but now I tend to play it more than before ) KK, QQ. You can also play jacks by limping or all in but it is a very weak hand for all in situations.