First, be aware that the Chen formula can only be a very rough guideline as to whether to play your hand. It is not the be-all and end-all. Also note that Bill Chen himself said that the formula can only help inform you what hands to play. It can't tell you when you should check, call, raise etc. That said, hands that score well on the Chen formula are generally much more playable than hands that score badly, and there is clearly something to the formula.
The guidelines at Simply Holdem suggest that you can use the following criteria for raising and calling, depending on your position -
Early Position
- Raise if 9 or higher
- Call if 8 or higher, otherwise fold
Middle Position
- Raise if 9 or higher
- Call if 7 or higher, otherwise fold
Late Position
- Raise if 9 or higher
- Call if 6 or higher, otherwise fold
Those certainly aren't hard and fast rules, but they might be helpful for a beginner. In generaly, we can make the following statements about how you should player tighter/looser depending on various other factors.
Position
You need a much stronger hand to call or raise in early position than you do in late position. In late position you can afford to play looser, since you will retain the position advantage on subsequent rounds.
Raise in front of you
If there has been a raise in front of you, you need a much stronger hand to call than if there has been no raise.
Number of callers
In general, you should have a stronger hand to call or raise when there have been many callers in front of you (because of the danger of flush and straight draws). The exception is when you hold a drawing hand yourself (eg suited connectors, or a small or medium pair). In that case you may want to call even if your hand isn't that strong at the moment, because of the implied odds when you make your hand.
Short stack
There is some pressure to play looser than usual if you are short stacked, since you don't want to waste your stack paying the blinds while you wait for a good hand.
Antes / no antes
The larger the antes relative to the typical bet, the looser you should play. This is because all that ante money in the pot is massively improving your pot odds.
Limit / no limit
For beginners, I'd advise playing tighter in a no limit game than in limit, because it's easy to lose control of the game to a better player and you're prone to throwing good money after bad.
Number of players
With few players (3-6) you should player looser, since there is less chance of another player having a strong hand, and your share of the blinds has increased, so waiting out rounds to get a great hand is expensive.
