How can you identify what your physical tells are, and hide them? Once you've identified your tells, should you work at suppressing them, or is it better to deliberately give your tells at strategic times?
Edit: this assumes live games, and not online play. Bet-size tells are also not relevant to this question.
Even though seeking to completely control one's tells is a good goal to aim for, it may be a good idea not to give them a chance of happening.
One way of accomplishing this, noted in Phil Gordon's Little Green Book, is not to look at your cards until it is your turn to act (before the Flop in Texas Hold'em).
Or, to state it in a more general way:
The less we know, the less we can give away.
Of course, knowing less is often a disadvantage, so we'll have to weigh up carefully how much information we'll keep from ourselves in order to keep it from attentive opponents. However: Not looking at our hole cards before we have to means less time for our opponents to get a read on us, while we would probably not profit from knowing our cards at this stage. Furthermore, it prevents us from losing interest in a hand prematurely when we could be observing our opponents carefully, trying to put them on a possibly range of hands.
Another solid strategy (also taken from the Little Green Book) is not to vary the size of your bets according to the strength of your hand. This seems weird at first, but when combined with a tight-aggressive approach, this can go a long way in concealing your hand from your opponent. After all, the real reason we are trying to avoid tells is that we don't want our opponent to know, or have a good guess about, the actual cards we are holding - betting medium hands weakly and strong hands strongly while checking/calling when we have a draw will give our opponents a good idea about what cards we are holding.
Corollary: play less hands (tight), and do not vary your bet with the strength of your hand (i.e. bet the same amount with JJ, AK and maybe even occasionally T9 suited before the flop). However, once in every few hands, reverse your betting pattern by slowplaying a big or medium-strength hand, confusing those who are trying to analyze your play.
Every time we bet or raise, we are forcing our opponents to make decisions. The way they react to this forcing serves as an indicator of the strength of their hand and their willingness to play it - we are forcing them to give us information about their hand, while simultaneously representing a strong hand (whether we have one or not).
This answer contains just several small aspects of the big picture - a true answer to your question could fill books (and books have been filled with just that topic). However, I hope the above thoughts provide a starting point.
In addition to codesparkle's great advice, I think the other key thing (as noted in Joe Navarro's Read 'Em and Reap) is to replace your tells with routine. Have a set (and comfortable) base position that you return to every time, likely with your elbows on the table, hands covering your mouth. Consciously strive to make your actions (looking at cards, looking at chips, watching other players) the same every time. Having a routine that you are consciously focused on repeating not only makes your actions predictable and consequently boring to anybody watching you such that they move on and look for an easier target, but it also gives your brain something to focus on, keeping you in better control of the tells you're not even aware of.
It's challenging to accomplish, but taking a long view of poker is a good way to hide tells. If you don't let yourself get caught up in wishing for a specific outcome or action, then you are less likely to show nerves or excitement/disappointment. Dissociate your thoughts from the money and approach each situation as you would if the situation were posed as a question on this site. Try posing the question to yourself in the hypothetical. Don't think "What should I do here?" Think "If I were in this situation, what should I do?" Then when you've decided what to do, do it with the knowledge that whatever the outcome, you've made the correct decision. This will calm your nerves.
For example, if you decide to make a big river bluff, don't do it because you want to or because you "think he will fold". Do so knowing that sometimes he will call and sometimes he will fold and that is ok. It's ok because if you've done the analysis correctly, you will come out ahead in the end.
Don't talk during hands. The less you communicate, the less you risk giving away.
Don't try to stare down an opponent. A lot is revealed in your eyes. I like to look at a spot on the table in front of me if I am being scrutinized by an opponent.
Take your time. Especially when you've already made up your mind. Make it a habit to count to 10 slowly inside your head before acting. This way, you don't give anything away in hands where you really have to think. (Important: Don't do this if you already know you're going to fold, or at all during preflop play. That is just annoying to the rest of the table)
1) When you receive your hole cards - relax, hold your breath and catch a moment when everyone is busy looking at their cards. Then look at your cards slowly and then think about something neutral (concentrate on a thought how you don't really care what you're holding right now).
It's better to look at your cards before your turn to act, otherwise you'll be on the spot and people will be watching your immidiate reaction. Especially people who have position on you.
2) Think about your hands. Where you keep them. If you shuffle chips like a pro - everyone will be aware of your experience at the table. If you try to shuffle and make mistakes - everyone will spot a rookie. Keep your hands calm and feel relaxed.
3) Take a second before any action. (Don't reach for your chips with hands shaking when you want to bet).
4) watch your legs.
5) You can watch "high stakes poker" or "poker after dark" on youtube and study the players behaviour.
6) but +1 for "not talking" advice. People who talk a lot - tend to play more loose ;)
Watch people with tells and don't do that! Hint, everyone has tells.
Everyone has a rhythm to their game, and everyone gets off that rhythm somewhat when a hand comes along. The players that are toughest to read are the ones that are able to stay on that rhythm when a hand comes along.
It is not important to be any particular way, there is no most effective poker face that works universally for everyone. What's most important with hiding tells is to get into a rhythm that fits your natural personality and state of being, and maintaining that rhythm rather you are in a hand or not.
Be aware of the little things you are doing. Many players with a bigger hand pay more attention then when they plan on folding. Players wanting to bet or raise tend to glance at their chips. Players ready to fold, cap their cards differently, don't glance at their chips, change their body language, shuffle their chips differently Etc. Etc. Watch what they do and don't do that!
One of the simplest processes to get into a rhythm that I use is simply pay attention to the game with the same intensity rather or not I am in a hand. This also has the benefit of picking up a lot of things on players that come in handy to make a profit. I am kind of the quiet type, so it works for me. Some players love to talk, and that can also work well for that type. They just give you more tells then you can possibly sort out accurately, a little like hiding in plain site.
Wear dark glasses, it's much harder to read body language tells without seeing the eyes.
