Absolutely what Kev wrote. There's usually no need to send the whole project, either.
Establishing your tempo and sample rate up front is crucial.
It's also a good idea to leave a few blank measures at the start of the tracks.
You might want to create a click track with EZ Drummer or Edirol VSC(the GM synth included with SHS4).
Don't use count-in or the regular metronome. The metronome in SHS4 should not record, and if it does, you are set up wrong.
The click track can easily be muted for the final mix.
Wav files are the best quality, but are too large for email.
SHS4 supports wma export, and these run a close second.
MP3 is fine for reference tracks, but use higher quality formats for the actual working tracks. If you must send MP3 working tracks, use a high bitrate.
I've been involved with collabs that had as many as a dozen contributors. Keeping the file exchange slim was effective and made the whole thing manageable.
One very important thing is to send complete tracks, not clips.
For instance, you have a single triangle hit in measure 96. If you send just a short clip, it will be difficult to line it up.
Export the whole track, including the 95 measures of silence.
It will start at 0.00.00 and all is good.
Use "Save As" often, and definitely save a new version after the addition of a new track.
If something doesn't work, you can always back up and try something else.
A rough outline of a collab might run something like this:
1.Establish BMP at 110, 4/4 time. 44.1k sample rate, key of C.
2. You record a bass line on track 1, drums on track 2.
3.Export this as a wma or wav file.
3a. If you exported as wav, convert to MP3.
4. email wma or MP3 to your friend.
5.Your friend opens a new, blank project, and imports your file into track 1.
6.He records a guitar track as track 2 in his project.
7. He selects and exports only track 2, and sends it back to you. This should be at least wma or preferably a wav file.
8. You create track 3 in your project, and import his audio track.
And so on. Add individual tracks as the project builds.
Be sure the Now Time marker is at the beginning of the project when you bring in new material. Hit [W] (rewind)first to be sure.
Collabs are a blast. Don't make it harder than it is, and have fun.