Your Start hand

The first decision you need to make in texas hold'em is if you have good enough cards to go with. Occasionally, you bluff at the pot, and it happens that you're lucky and it comes up cards that fits even with a bad starting hand, but in the long run serves to just go with when you have good hands on hand. Why you should set high standards for your card in the hand to go with.
The most common mistake in poker is to join in too many donors with a chance-like or sub-standard cards in your hand.
A good starting hand in Texas Hold'em is usually considered to be the following cards in descending order:
A-Kf (ace and king of the same suit)
A-Qf (ace and queen of the same suit)

The basis for this ranking are normal conditions in Texas hold'em. That you are 7-10 players around the table and that it is recorded average tight, ie approximately half fold in the first round of betting.
In practice, it also matter what position you have at the table, etc. but the list reflects the starting hands that experience generates the most money in the long run.
The chance to get one of these top ten hands at the dealer is one of 23.
A bit more difficult to assess the situation is when you get Ax Ie an ace and another card below 10. Are your cards the same suit, you have 1 chance in 25 to get a flush. Not very strong odds. Of importance is also how high your other cards are. The lower the rank, the weaker starting hand. The risk is that someone else has Ay where their kicker is higher than yours.
This may be important how the other is investing. Have not joined in the first betting round may not have two face cards and then you can raise with Ax. If the other folds, you win anyway blinds. If someone stays you have the chance to get a pair of aces, the highest pair going to get and you win if someone else also has a couple, but a lower one.
Have several other players before you just joined, you can still improve, especially if your kicker is loud and in color with the ace. With a lower kicker that is not the same color as the ace, you should consider calling instead of raising. If the flop helps your hand, you can then beta-hard. Miss you, you put your hand and it has just cost you one bet before the flop.
If one or more players increases it may be time to meddle with an Ax starting hand if you think they have better cards than you have.
You raised pre-flop but miss, and it is you who speak only to one or two others, you can cooperate to bluff a hit, but if someone else speaks first and operate, or if you get a raise against you, just add itself.

The 10 worst hands you can get and that it almost never is justified to play are:
2-7 off suit. It is the lowest two cards you may have which can not form a ladder together. Even if they are in the same color so you can at most have a very low color and form one of those couples with the cards on the table is the low pair.
3-8 or 3-7
2-9, 3-9 or 4-9
4 -7, 4-8, 5-8 or 3-6
Face card low card in different colors. The risk is great that someone has a better hand. The more players there are at the table, the more rarely is it playing like this happens. Is it just you and one of these happens more games just because the odds that someone has a better hand then decreases.
Aces low cards of different suits. This type of hand is only slightly better than the previous - the win sometimes but is not playable by many players around the table. you are 4 or more around the table, you should watch out, especially if someone else has raised.