First of all, rookies are almost always too confident in their hands. They will play a hand which no expert would recommend, but will fold in late position a hand which advanced players believe it’s a playable hand.
Don’t be afraid of folding: some weaker players consider it's a matter of pride in playing more hands, but in reality, playing more hand makes you more likely to lose . You have to look at the professional poker players who play less than 20% of their hands, whereas beginners will play up to 60% of their hands.
Then there's the question of what hands to play. There's not an easy answer for this question: it depends not only on your cards, but also on the number of your adversaries, on the bets of the opponents before you and most importantly, your position.
When you have just two opponents the best hand is going to be weaker, so you can play even hands that are not premium. However, if you play against nine other players, if you go in with a weak hand, it's almost certain there will be someone with a better hand.
The position is an important part of the strategy that is forgotten by many beginners: when you are the first to make a bet, you don't know what your opponents are going to bet, so you risk more by calling. This is why it's better not to call the blinds unless you have some serious hand.
However, if you are in late position, you see what the other opponents bet and you know exactly the cost of seeing the flop. Some players, when seeing that there's no one to raise before him, will simply raise a lot, so that the others will fold. This technique is called "blind stealing".
