The Kinds of Poker Tells
Poker tells are divided into two main categories: conscious or acting tells (or "tells from actors"), and unconscious or natural tells (also called "tells from the unaware").
Conscious Tells are executed by poker players to give the impression that they want. A poker player wants only one of two things: for people to think they have good cards, or for people to think they have bad cards. Almost always, they will want you to think the opposite of what is true.
For yourself, you'll want to be very effective in giving acting tells. When it comes to your opponents, you want to be able to read through these tells.
Unconscious Tells are natural mannerisms and habits of poker players. Everyone has habits and mannerisms. But in poker, these can work against you, "telling" other people what kind of cards you have.
For yourself, you want to display as few unconscious tells as is humanly possible. When it comes to your opponents, you definitely want to see these tells in them.
Conscious tells are almost always exaggerated and artificial - the player wants to give you time to see these fake tells. On the other hand, unconscious tells are fleeting and hard to detect. The player tries to hide them if he or she is aware of them at all.
Good Hand Poker Tells
As a beginner, you are only concerned with identifying the basic poker tells and what they mean.
The first thing you want to know is, "What tells indicate my opponent has a good hand?"
Common "good hand" tells are:
Feigning disinterest in the game by looking bored or tired. Looking away from the table. Avoiding eye contact with other players. Stealing quick glances at the board. Looking briefly at their chips, or yours. Sighing, frowning, or otherwise faking some negative emotion. Sharing cards with a non-playing companion. Betting softly and non-threateningly. Being relaxed. Suddenly playing and looking interested after folding many hands. Trembling hands, sweat and other signs of excitement. Sometimes trying to intimidate a specific person (to dare them into the game).
Note that the above are a mixture of acting and natural tells.
In general, a player with a good hand wants to look as ordinary as possible when they are betting, and as uninterested as possible when not betting. They want to keep you in the game so you can put money in the pot. After all, they expect to win.
Band Hand Poker Tells
Now you want to know, "What poker tells suggest a bad poker hand?"
A bad poker hand can also mean a player is bluffing so these tells can also mean someone is bluffing:
Staring other players down. Trying to intimidate no one in particular. Studying cards for too long. Studying chips for too long. Looking at the board for too long. Making exaggerated gestures when betting. Strong voice when betting. Being too still or holding one's breath (very common when bluffing). "Accidentally" exposing a high card. Prematurely taking the pot. Betting out of turn (they want you to fold).
Conclusion
These are basic poker tells for spotting players with good hands and those with bad hands. These are not fixed rules. In fact, the more you know a player, the more personalized or unique their tells must be. These are only general tells. Get to know your opponents as much as possible for more accurate tells. Good luck!