I love doing backwards recording. When it comes off, it's like no other effect I know. Even now I've switched to a standalone DAW, I had to buy one {a Zoom MRS-8} specifically for the purpose of backward recording. Though I record stuff digitally, I still act as though I'm in the analog domain.
How backward recording is done really depends on which specific instrument or element one is recording. For example, say you are doing a backwards guitar solo. You can work out the notes in sequence normally and record it or hum it or whatever, then turn the tape around and you'll hear it all coming backwards at you. You can either learn the guitar part as it now is {backwards} and then record it or record it in sections and join each section once you've recorded all of them. Because of the nature of the sucking and swooshingness when you turn the tape back to normal, you won't be able to tell where the joins are if you do it well. If you've done a scratch recording, putting it in the mix {if you have the tracks spare} at a very low level can strengthen the sound when put together with the backwards recorded part.
Something I've done before to great effect is to turn the tape around and improvise to the backwards backing. You'll never know what it sounds like until you put the tape back to normal and therein lies the risk. But I've often been pleasantly surprised by what I've come up with.
It should be pointed out that not everything sounds good recorded backwards. I've not been impressed for example, with pianos, while drums can be really hit or miss, depending on the context. Cymbals can be fantastic though. And using effects like reverb, echo or delay backwards {so they appear before the sound when turned the right way} can be magnetic and dramatic and not a little spooky !
Also, remember, especially if you are using a portastudio, the way tracks correspond when you turn over the tape, so if you are using an 8 track for instance, track 1 becomes track 8, 2 becomes 7, 3 becomes 6, 4 becomes 5, 5 becomes 4, 6 becomes 3, 7 be4comes 2 and 8 becomes 1. So if you've got stuff on tracks 6, 7 & 8, when you flip the tape, they'll be on 1,2 and 3. It sounds simplistic but it's amazing how easily one can forget and end up wiping something that was already a keeper.
