Practise is not only needed if you want to have the techniques at your fingertips when you need them. It is necessary for complete routines, acts, or tricks. Seems to be logical, but is seldom put into practice.
There are many ways to practise: a drill, a run-through, a short-time practising run, mental training, and many more. In theatre, there is ‘dress rehearsal’, meaning rehearsals in full costume, running from beginning to the end. This practice sadly is seldom seen in magic (at least from amateurs).
Practise routines. After getting acquainted with the main technical stuff, such as moves or gimmicks, you rehearse the entire routine. The complete array of movements, the order in which they happen, the patter or music.
Whenever you start a rehearsal, make sure it is a complete rehearsal. Don’t go through the routine sloppily. Go through it with all the patter, gags, presentation, costume and props. Act as if you were performing for a real audience. Imagine spectators sitting in front of you in your rehearsal room. Cut out eyes and faces from magazines and glue them to the wall. It will fool you into addressing real people.
The difference is that with a rehearsal, you get the timing and the feel for a routine. Going through it from the beginning to the end, it will feel awkward in the beginning. This is more effort on your side, rather than just mimicking a few moves and rushing through the routine.
But it will give you a sense of the timing, duration and the technical problems. Only through a thorough rehearsal, I find out many small technical details that I would have never found otherwise. These would have been disastrous in performance, but I could avoid them with the rehearsals.
Just practising isolated moves is not enough. Go through the complete routine and presentation.
The world’s foremost cellist, Pablo Casals, is 95. He was asked one day why he continued to practise four and five hours a day. Casals answered, “Because I think I am making progress.”