For Press Releases I always give a bit of history and a short piece about the 12" and sometimes feedback and reviews. Plus the release date with full artwork as well...

As Henry has pointed out, there's a few DJ's out there that never reply, X them off the list but I've been surprised by a few and it does depend on your tunes - for example Dave Clarke always replies, even tho he gets loads of shit on the net, I've always found his advice helpful. Pick your targets carefully - it's easy to see what they are into from their charts.

Always get the best mastering you can afford and don't fool yourself that you can pre-master, ever. Get the levels right and leave it to a good pair of ears - that way they will have more to work with. I've no idea who masters Reeko's records but I'd like to kill him/her.

Start your own mailing list and let people know stuff in advance, not to early tho - keep it short and sweet. Get your friends to get the record from the local store - this helps support the label and the local market.

Know your market and what is selling where - you might think the latest Umek 12" was a pile of shite but it did 12,000 units - go figure ;)

Martin