Poker is a game of strategy and psychology rather than strength and luck. Whether you play it professionally or for fun, it requires a lot of mental energy and is very taxing on the brain. You need to be able to quickly make decisions and read other players in order to maximize your win rate. Observe experienced players and learn from them to develop quick instincts.
The first thing you need to understand about Poker is that hands are good or bad only in relation to what other players have. There are many hands that look great but lose to other better hands because the player is holding a strong hand. For example, a pair of kings is a solid hand but can easily lose to someone holding A-A. Having an excellent hand only counts if you can get people out of the pot.
It is also important to remember that most new players will have crappy hands. Therefore, it is usually a good idea to bet because you can often make money off of them. A lot of beginners feel timid about playing trashy hands so they will just call pre-flop but this is a dangerous habit. The flop is likely to come and if you are just calling then your opponent will see the flop for free and can bluff you out of your trashy hand.
The third round, the turn, is when an additional card is revealed that everyone can use. This is usually a good time to check/call/raise/fold and will give your opponent a chance to put together a good three of a kind or higher.