For the love of Pete, throw your hand away! (most of the time)
This is usually your first opportunity to get rid of your hand--something you should be doing fairly regularly! You should have a decent pair (split or unsplit) or three high cards that are either connected, suited, or both if you are playing a stud-high game. For hi/low games, you can also start with three cards 6 or lower that contain an ace. For more information about starting hand values see our Starting Hands section.
If you have the lowest card showing you'll be forced to bring in a small bet, but generally you should fold if it is raised behind your bring-in and you don't have a reasonable starting hand.
Be careful when you are out of position
On the first betting round you need to evaluate where you are in relation to the person with the lowest card who is opening the action. When you have to act early and are holding a marginal hand (a pair of split tens for example) and there are lots of overcards left to act after you it is often right to lay down your hand in advance of potential raising. You should use your feel for the table to know whether you can get to the fifth street relatively cheaply. Usually you'll be facing only two major decisions in your hand and the first is whether to even get involved. Being extra-frugal here can save you a lot of money with second-best trap hands later!
Try to put your opponents on a hand
The Stud Pros call this putting someone on a "hand in three" or determining your opponents most likely holding based on the cards you've seen in the deck and the action on third street. In a low limit game this is more difficult, but still doable to a certain extent. If you are playing at a full table you will have seen 10 of the 52 cards in the deck (your two Hole Cards and the 8 cards dealt face-up to you and your opponents). This is a lot of information which you can use first to determine if your cards are live (in addition to the ranks that match your hand you also need to notice the suits and ranks you'll need to complete a flush or a straight draw even if it is a backdoor draw. Second notice which of your opponents cards are counterfeited on the board and then based on their play of the opening try to put them on a range of probable hands.
If you're drawing make sure it is a better draw than your opponent.
Obviously you can't see your opponents Hole Cards directly, and you may have an AQ high flush draw of one suit and they may have a hidden AK high flush draw of another suit, but generally the rule is this: Only draw to ace-high flushes and only draw to broadway (ace high) straights. The obvious exception to this rule is when you are in a hi-low game when a wheel draw is very strong especially if it has a two or three card flush draw with it.
When you do play, make them pay
In most cases you can raise your hand if you are going to play especially if most of your cards are live. Generally you'll be starting with better cards than your opponents and in a very-multiway pot you are charging the worst starts a premium for viewing the next cards so even if you don't have the very best hand to start you have a more-than-fair-share percent chance to scoop the pot after all the cards are dealt.