You mean Blackjack cards counting? FYI, these guides are available all over the internet FOR FREE, they don't work at online casinos because you don't know how many deck of cards does a casino uses and when do they shuffle and last but not the least, counting cards is illegal, anyone caught doing this on a floor casino gets banned for life.
Edit: By illegal, I mean as per Casino's own rules, following which they can ban you if you're found doing this as they have a "right to refuse services to anyone". Moreover, the casino maintains a list of such counters which are shared with other casino owners, thereby blocking them from other casinos as well.
there is about 5000 free articles about this on youtube and google.
gotta love paying for free information.....