If there is one thing that you must learn right away when you are considering playing any poker game and in particular a no limit poker game, it is that the initiative is critical to winning pots. Even in larger games, you are not going to be very successful by checking and calling with your hands; you are the very least have to take the initiative when you are backed up by a h2 holding but you also sometimes have to take the initiative when you are not backed up by anything whatsoever. Regardless of what the cards you have are however, the manner in which you take the initiative is still going to be the same. Two ways that you can do that are through the check-raise move and the all-in move and these are discussed in more detail below.
When you check raise, you do exactly what the name implies. When it first comes to you in a betting round, you check it down in the hope that someone will bet. If someone does go ahead and take the initiative of betting, you can then seize that initiative from them in a powerful way by raising the bet that they just made. There is another similar move to the check-raise called the call-raise, which is essentially the same thing but instead of checking, you are calling a bet made by a player before you in the hopes that a player behind you will raise and allow you to get three bets into the pot instead of the two bets that would be there if you raised right away.
Either way, the check-raise will let people know that you have a hand that is not only strong, but one that is so strong that you had no problem checking or calling and potentially letting another card come out in the game. People usually check-raise only when they have extremely strong hands, or alternatively when they are trying to represent that they have extremely strong hands. However, check-raising is a tactic that is lost on most players that are not of a specific level of skill in the game, so make sure that you only use the tactic when you are playing against players good enough to know what it might mean.
All-ins are like check-raises in the sense that it is possible for you to check-raise all-in, but they are different in the sense that they mean something different. All-in means that you bet your whole stack, which, if you are playing in a no limit or pot limit game, can be a very large amount. All-in moves are used once again primarily to seize initiative and bluff people out of pots that you want to take down without having to show your hand down. All-in moves can be very powerful in that way, but if your read is off or you use it at a poor time in a hand, you could end up losing your whole stack and ending your day of poker pretty quickly.