Your position at the table is very important. This does not mean that it is important which chair you decide to sit down on. What I am referring to is your relative position, your position in relation to the dealer button. The further from dealer button you are the stronger position you have.
This does however not mean that is doesn’t matter where at the table you choose to sit. Choosing the right chair can impact your game greatly. If there is a very aggressive player at the table that like to raise with almost anything than it is good to sit as closely after this player as possible. This way you get to take advantage of his aggressive play and bluffs without getting pushed out of pots you already bet on. You can reduce your chip leakage by being seated in the next few seats after this player.
Your relative position on the table should guide your betting strategy. The later position you got the more information you got and the more aggressively you can play. You should adjust all aspects of your game accordingly. Pre-flop you should play a lot more conservatively in an early position than you do in a later position. In a later position you can chose to see a pot with a less than optimal hand. This is due to the fact that you are in a lot better position to buy the pot by placing a large raise if you are playing a late position and know that the players before you already have checked. Buying the pot is when you make a rise to make it too expensive for the other players to stay in the pot in the hope of improving their hands.
In an early position you should normally play conservatively. When you play in an early position you have very little information available. This is especially true after the flop. On the turn and the river you have more information from the earlier betting rounds but you still have very little info on how the last card might have affected the hand. This is the reason that you should avoid playing too aggressively. It can often be a good idea to check and let another player open the hand. If you have a good hand you might benefit from a later player trying to buy the hand in which case you can cold call him in the hope that he makes a continuation bet on the round.
In a mid position you have a little more information but you should still play rather conservatively. You can play a little more aggressively than you would in an early position.
When you are in a late position it is time to switch your game up and play a lot more aggressively. The later the position you have the more information you have. You should try to control the hand if you play from a late position and you can try to buy the pot even if you did not hit the flop.
Adjust your strategy in each position until you find a strategy that works good for you.