Card Counting itself is so easy a teen-ager could do it. Doing while in a social setting at high speed, without looking like it is tough.
The easiest system is the + - system. A, K, Q, J, 10 are all –1. 2, 3, 4, 5, 6 are all +1. 7, 8, 9 = 0. 1 complete deck = 0. Take the count you have at that time and divide it by the estimated number of decks remaining in the shoe. That number is the true count. If your true count 1.5 – 2.5 double your bet. Up to 3.5 triple. 3 to 4 or more in a true count is rare in strip hotels. The probability of a high true count drops for every deck that is put in the shoe. Also the fact all casino’s only use half of each shoe also will reduce the number of high true count opportunities. Also if the true count is over 2 buy insurance. If the true count is less than –2, only double down and split on the best of opportunities, (i.e. you 11, dealer has 6) don’t force it. Card-counters are discovered not necessarily by winning a lot of money because that could happen to anyone. They are found out by their strategy in the game that goes against normal strategy, such as the 2 situations above. Normal players never buy insurance yet if you buy it and win 60%-70% of the time something is amiss.
Practice card counting with a deck of cards just by turning them over and coming up with the total of 0. Make sure you can accurately count them about as fast as you can deal them at a poker game. You may need a deck estimation chart which just takes the average number of cards a player uses times the number of players times # of hands. But I have typed enough for now you get the idea. One last thing card counting is all work and no fun.