Research has shown that your brain registers the same impulses whether you mentally go through actions in your mind or actually do them with your body. So it goes without saying that you can learn the tai chi form you’re working on by going through it in your mind.
This technique is a “mnemonic” tool for improving memory. Mnemonic is a Greek word for a memory tool, or techniques for remembering information difficult to recall. The process is simple. See it in your mind’s eye, then feel it in your body as you move step by step through the sequence. This is a visualization mnemonic that can transfer to and improve other areas of life, not just tai chi.
You can find many websites providing tips and other information on improving your memory skills.
Another helpful tool is to play music while you do the form. Many tai chi practitioners do play slow music while they do form, such as Chinese guzheng instrumental music or non-percussion flute music. I have opted to do this very rarely since silence itself is music to my ears, but for beginners I see value in it. It helps to calm the nerves and everyone can benefit from that.
Many practitioners spend a lot of time and effort remembering the names of moves and postures, but I have not done that. Other than to remember main postures, such as single whip or wu ji and so on: at least at first, early practitioners get caught up in remembering the names of moves rather than the moves themselves. That is a major distraction. I recommend learning the moves first, then worry about the names later when you are more comfortable with recall.
One more tip: if the thought arises, then that moment is the time to practice tai chi. I often ask learners what they have practiced since the last time we practiced together. And often they say sheepishly, “Well, not much.” I hear “nothing” regularly. Then I ask, “Did you think of tai chi at all during the week?” and often the answer is yes. Then I say, “That is the time you should practice, because it is the spirit talking and reaching out and giving you a chance. Don’t pass it up next time you hear it speaking.”