The most basic strategy is do not play unless you can afford it and also are better than average cash player. No Limit tournaments are a different matter as the most you can lose is your buy-in.
No limit poker is all about knowing when to push a hand and when to fold it. No limit poker is a game of serious aggression and not for the timid of heart. It is a game where money is power and can be used as a weapon, often when faced against a player who has gone all in its safer to fold unless you have a really strong hand and are confident. This is true in both cash games and tournaments. Watch any tournament and you see players go all in with small pairs and other players with better pairs fold. The aggressive player usually an advantage in a No Limit game.
Unless you are on a rush of cards and winning hands be careful of calling large bets on the come. Hunches can be valid, but realize that a hunch may be just a strong wish.
Tournament play is far different than cash play for the basic reason that the buy-in fee for the tournament limits the cost of the game. A cash game is only restricted by the willingness of the player to purchase more chips.
A limit game is not advantageous to an aggressive player as the amount that can be bet is set, for this reason the overall play of the game is different. A no limit game lets the player decide the amount that can be bet at any time. This also opens the game to more bluffing and position play. Two players that both hold ace king may be decided by who gets to bet first and the size of the bet. Here position may decide who wins the hand.
Cash game no limit or even high limit is a game where the experts play and is not for an beginner in most cases. If the money is important to the player they should pass on the cash game, as the size of the bets will influence the way they play and could lead to poor decisions.
On the other hand, the non-expert can win a no limit tournament as the money loss is limited to the buy-in fee. This is the reason that you see so many young players at the final table on the TV tournaments. That reason and the fact that they have played for hours on the Internet make them very dangerous.
Any player paying for the buy-in can play in a no limit tournament. This absolutely not true for the no limit poker games.