One hand that can be very effective is known as suited connectors (running cards of the same suit). The primary reason for playing them is that they have the potential to win massive pots, as you could make a straight or a flush and take all your opponents chips. In addition, suited connectors are often well disguised if they end up making big hands like two pair or trips, these also have the potential to build your stack.
Suited connectors' strength is also based on how big the cards are. 2c3c is a much weaker hand than QsKs. The higher the suited connectors the better starting hand it is, because they have the potential to flop bigger pairs so you could win the pot with top pair or even just by having the higher cards.
Also, if the board comes 678, someone playing 45 is going to be in a lot of trouble against someone playing 9T.
Suited connectors are best played when you are playing deep stacked NL Hold'em in multi-way pots. More opponents improve your odds because you want to make sure you get paid off if you make a big hand, you are about 6:1 to flop either a straight or flush draw. This means that you will not flop a draw the majority of the time, so the more players involved in the pot the better.
In short handed games with six players or less, one strategy I see many successful players use is to play them aggressively, often raising and even re-raising before the flop. That way you have taken control of the pot, and even if you pick up callers, you can bluff or semi-bluff if you miss the flop. For example, you are playing a $5/$10 NL Hold'em game five handed and you raise to $35 pre-flop with 7d8d, both blinds call. The flop is 3s4c5d. You only have eight high and both players check to you. You should definitely bet here. There is $105 in the middle, so Id recommend betting around $75. If they raise you, you have to fold, but there is a good chance that they have both missed the flop and will simply pass. If they do call you have 4 cards to make the nut straight, six cards to make a bigger pair in case they are calling with A5 A4 etc and also a back door flush draw.
What decides whether you make or lose money playing suited connectors is the marginal situations that you face when playing them. For example, you are playing $5/$10 NL Hold'em and have a $1000 stack. A player raises to $40 and you call from the big blind with 9dTd. The flop comes 5s6c9h. So you have top pair and a weak kicker. What is the best strategy now? You are in a Heads Up pot so your hand will often be best. What you must do is minimise your losses if it isn't. If you check call pot sized bets all the way you could lose most of your stack if you are behind. I would recommend making a weak bet at the flop if you are first to speak. So in this pot you could bet $35 which is less than half the pot. If your opponent folds, you have won the pot right there. If they raise you $100 more you could call and see what they do on the turn. They may have just raised you because your bet was weak, and will be scared by the fact you called their re-raise. So they will probably check the turn if they don't have a big hand. If they make a big bet on the turn I would fold because it's unlikely the pair of nines is winning. Don't get stubborn when you flop just top pair with suited connectors, especially if you are facing bets in multi-way pots.
Suited connectors will make you money if you know how to play them correctly. By selectively picking out the situations to enter the pot and knowing when to draw and when to fold, you will be able to improve your game and develop a bigger edge on your opponents.