There are many card counting systems to choose from if you want to learn this skill. Among the many different types you'll find you can be sure that all of them will have each its own weaknesses and strengths, advantages and disadvantages. Before anyone can choose a card counting system that works for him, one would have to know what to look for and what criteria can be used in selecting a card counting system.
Some card counting systems will be effective in multiple deck games and quite difficult with single deck games or card games with less decks. Some are easy to learn but can work well only in single deck card games. One important thing to look out for is to check what game you really play. Whether you're into single deck card games or multiple deck games, select the card counting system that works better for such games. Better yet, learn at least two card counting systems - one for single or fewer deck card games and another for card games using more decks in a shoe.
Another important thing to look out for when choosing a card counting system is to gauge one against the time you spend playing in a week. If you play in a day for longer hours then it is better to stick with simple card counting systems that with the really complicated ones. Complex card counting systems are much more effective but harder to maintain during longer periods of time.
Simpler card counting systems will be better if you play for five hours giving you less strain and you avoid committing mistakes along the way. More complex card counting systems are good for shorter gambling sessions, it will strain your mind during a short span of time but will yield more in a shorter gambling session.
A card counting system's betting efficiency and playing efficiency should also be considered. The strange part about card counting systems is that if you choose a system that has a better betting efficiency you can expect it to have a lesser playing efficiency. The matter also works vice versa for other card counting systems.
An example would be in a six deck blackjack game, card counting systems with higher betting efficiencies will be better - these usually counts the Ace as an 11. But this won't work for a single deck blackjack game. For a single deck game, a card counting system with a higher playing efficiency is more recommended.
These are the things you should look out for when choosing a card counting system that works for you. These card counting systems will have their own strengths and drawbacks.