- Copy early. Usually the character copy is available before the PTR is up or the client can be downloaded. Keep an eye out on WoW Insider or some other news site for when the US copy is up; in my experience the EU one is up too. The wait time when the client isn't available was 4 hours for 3.0.2.
- Patch often. You download the PTR client, install it, logon, then you get a patch. You install the patch, logon then you get another patch. You don't log on for 5 days and get another patch. It is best to logon every day even if you aren't actually going to play on the PTR just to get any patches.
- Download a PTR patch while playing real WoW. You cannot log onto the PTR and real WoW at the same time, but you can get the patch downloader started, then play WoW.
- Log on even if you have no toons. You can log onto the PTR even if your characters are not copied across. This will get any patches downloading. So if you have the PTR client and are waiting for your toons to be copied, log onto the PTR anyway and grab those patches.
- Report everything. I tend to report anything I find however minor. The reporting interface is pretty good and quick to use. For obvious stuff, other people have probably already reported it, but maybe not. You can report anything which seems odd or wrong as a suggestion; I hope Blizzard take notice of such reports, after all they have added a suggestion feature to the PTR client.
- Clone your gold. Send all your gold to the toon you are copying. Make a copy. Make another copy of the same toon. Repeat until you have enough gold on the PTR for whatever you want. When on the PTR, send all the gold to the one toon. Voila, mucho cloned gold.
- Have fun. Obvious really :)
Anything else anyone has?