This discussion is restricted to a single card counting system: the high/low (also called the plus/minus) point count. This strategy is very easy to master. Two other methods if you're serious are the Advanced Plus/Minus and the "Hi-Opt I" systems. The former is similar to the high/low but assigns fractional values to certain cards as opposed to integer values which are easier to add in your head. The latter method is considered one of the most powerful counting systems of all time.
The reason why card counting works is this: The player gains an advantage when a deck has a shortage of cards valued 2, 3, 4, 5, 6, 7, 8. When a deck has a shortage of cards valued 9, 10, Ace; the player has a disadvantage. If you can tell when the deck is rich in 9's, 10's, and Aces you can do one of the following things:
Bet more money when the deck is favorable to you.
Alter your Basic Strategy play to account for the favorability, thereby increasing the odds of winning a particular hand.
Now lets discuss the +/- Point Count. As you can see from the small chart below, a plus value is given to low cards, and a minus value is given to high cards. Notice that 7, 8, and 9 have a value of zero. This is because their overall effect is negligible as compared to the others.
As you may notice, this is a balanced system. There are 20 cards in a deck that are valued +1: two through six. There are 16 ten value cards and 4 Aces in a deck (20 in total) that are valued -1. The remaining 12 cards (7, 8, and 9) have a value of zero. At the end of a deck the count should be zero. A good drill to practice is to get a deck of cards, turn them over one by one, and keep track of the count. If you enter a game mid-way between the deck or shoe, flat bet until the cards are shuffled.
Once the cards are shuffled commence counting from zero.
A quick example using ten cards: the following cards are shown in the course of a hand: A, 4, 7, 10, 10, 9, 10, 2, 10, 5. the first value is -1 (the Ace) & the second is +1 (the 4) = 0 (the current total hand count). The next card is the 7 which is zero so disregard it. The next card is a ten so the total count is now -1. The next card is another ten, giving a total count of -2. The next card is a nine which has a value of zero so ignore it; total count is still at -2. Next is a ten, total count is at -3. Next is a two which adds +1 to the minus three yielding a total of -2. A quick look at the next two cards shows that the two will cancel each other out (-1+1=0). So at the end of a hand of ten cards dealt to 2 players and the dealer, the point count is minus two. This provides you with the knowledge that you are at a slight disadvantage. Your next bet should either be the same or a unit or two lower.
From this example you see that it would be easier to count cards if you play in a "cards-up" game. That way you can see all the cards as they are dealt and count them as they go by. Most online casinos play "cards-up".
When the dealer deals fast, just count every two cards. You still count each card but you only add to your total count after every two cards since many times the two values will cancel each other out to give a net value of zero, which doesn't need to be added to your total.
When there are other people at a table, all this happens rather quickly and you may miss a few cards here and there, which essentially invalidates your count. You can't control how fast the dealer deals, but you can slow things down when the dealer prompts you for a play decision.
For one deck, alter your wager according to the following table:
Example: After the first hand of a one deck game, the point count is plus four and you just bet a £5.00 chip. Before the next hand is dealt, wager £15.00 (three units of £5.00) as the above table mandates.