I see you are talking about some card games. The bookies introduced a lot of pair of cards because in blackjack at the beginning if you were good at memorizing cards you could easily beat the house.
Practice and patience are two things when you play card games that may give you an edge, this is mostly true in poker games.
Playing blackjack isn't as easy as one might imagine, we don't know whether the site is fair or there is cheating in it, because so far I've seen cheating on card games that frustrates me because the house card is always better even though at first he held a small card, but almost always being blackjack in the end. So the best practice in gambling is patience and luck, no matter you are a beginner or a long time player, if you have high patience and pure luck, then I'm sure you can get a good profit.
As long as you are playing on a provably fair casino so you should no worry to be cheated, right? You say that have been cheated, do you have any proofs that the site is really not fair or you just say it becauase you get more losses than wins?
One more thing, how can you say luck is a practice? Have you ever to practice your luck, if so then would you mind to share how you do it? Sorry, but it does not make senses for me.