help me learn a dance routine.

You need a mnemonic device. Maybe make the moves into a story. Say the first move's motion reminds you of squeezing orange juice, the next reminds you of the corpse position of old fashioned mummies, the third is like shooing away gnats. As you're dancing, you think: "Okay, time to have breakfast with that mummy... First I'm gonna make some juice, now I'm giving it to the mummy, now I'm keeping the gnats away from his stale corpse."

Even if you only get some physical practice time you should be mentally reviewing it whenever you can. In the shower, bus or drive to work, taking a poop, eating, whenever, where ever- you need to be mentally imagining yourself doing the moves as well.

practice and repetition practice and repetition practice and repetition practice and repetition. Just keep doing it over and over. Treat it like building blocks - get the first sequence down, then the next, and keep adding. Identify start/stop sections (verse and chorus) and practice those strings individually, then link them together. Listen to the music, over and over, while doing this.

Do it really, really slowly. Really really slow. Make sure you think ahead to the next move while you're doing one. Once you've got them stitched together, you can start going faster. And if you get stuck - suddenly, oops, what's next? - take that section apart in slow motion before working up to normal speed. Speaking as a pianist. And when you can't practise dancing itself, run through the sequence (like Specklet says) in your mind.

Listen to the music you'll be dancing to whenever you can, and associate the moves with the music, especially the transitions.

Break down the song into movements, associate the melody with each move. So in your head you should be thinking "step, step, wave (oh yeah), thrust.. left-right (uh huh), bump, bump, hop, hop.. etc." to the music. It really helped me learn coreographed sequences and even now, I can still remember the moves when I hear "Baby, One More Time" ha.

I'm with Specklet - make it into a story that you can tell yourself, give each move a name and have a way (however ridiculous) of linking them together. I have practised choreographed dances in the past and this WORKS!

Yes, lots of practice is one part. You don't have to do the actual dance - you can practice the moves very subtly while sitting down, at work, etc., and that can still help.

During those times you have at work, rehearse it in your head, even if that just means listening to the music and silently going "Macarena Macarena Macarena Macarena and Wannabe Wannabe Wannabe Wannabe now 5678 5678 5678 5678 then...." I can't do mnemonics, personally, though many people love them. Also, basically you have to know the routine so well that you are able to think ahead. As you are discovering there's a big difference between pretty much knowing it and knowing it down cold. By the time you start one move you should already know what the next move is going to be. (And if all else fails, cue cards?)