When the crowd is cheering at a table, it usually means the probability sides have actually switched, in which case, it would certainly be a good roll to sign up with the group! Even if you are sticking as a sideliner for quick breaks is fine; remember you are out to win, not out to show off! When you are in such a table, your battle is currently half won!
If you insist on " stalking " a table, you have to count the cards quickly, are there many 10s, Js, Qs, Ks, As dealt currently? These increase your probability ratings gain to win in blackjack. However it is no so easy to count, mind you.
The secret of blackjack is basic- when playing at a table, always try to double up. But you need to know when to double up. Like when you have a ten and the dealer has anything less than a ten. Again, try to split your cards. Like when you have two aces. Or when you have two 8s. Certainly the dealer must not be with a ace card. If so, you might want to surrender. Else just split two 8s.