Hi Gan,
Since that you are new to card magic (I assume that this is the branch you are focusing on), theory11 members will agreed with me as well, and I think you should check out Royal Road to Card Magic. It covers all the basics. OR you could buy Card College Volume 1-5. I heard amazing reviews from that book and there is a lot easy information for a begineer and definitely easy to follow.
Practise
In terms of practising, I try to practise everyday and it is always in steps. The first step is to practise the sleights. If you can master the sleights, I guarantee you that you will master the trick or the card effect that you are trying to achieve. However, be aware that you may not get for the first time and that's what magicians go through this process. It takes time, but at the end, it will be extremely rewarding. If you have time, please check out these threads. You will find these tips extremely helpful to your magic journey.
MagicHat How to Practise
Theory11 May 2008: Practise
Both links will give you helpful tips. I hope this is helpful.