Games that share the blackjack area
The only way I feel comfortable back counting is while looking like my attention is being paid to a non blackjack game. Most of the games that share the blackjack pit are great cover.
I chart the dice. It takes 36 rolls to get a "history" and may show unplayable conditions in fewer rolls. I refuse to place a bet without enough of a history. The pit usually asks what you think there is to gain. Just make something up about the sacred flow of the dice. If the game is crowded all the better, stand back from the table (closer to the blackjack table) while you track the sacred flow of the dice so other people can bet from the spot you might take if the dice flow favorably. Glance at the neighboring BJ table at key moments. If the count beacons the dice just "arent favorable" and go back to blackjack.
At the other end of the pit is the roulette table. Tracking the spins is very common in roulette. You can stay without much action waiting to "spot the pattern" while back counting. You can place amazingly small bets every now and then to sell it.
Any game that shares the pit is a great cover. Tell the dealer at an adjacent table to a blackjack table, I like card games what is so and so game all about stand where the table you are supposed to be studying as a new game has a blackjack table in the background. Ask the dealer and PB lots of questions about the house edge, how the game works and if there are any good sources the casino provides about proper strategy for the game because you want to try it but not until you are comfortable with how not to make mistakes. When conditions are right at the blackjack table say, Ill have to try this game next time after I learn more about it and go back to blackjack.
Thats my idea of cover play.