@alelink
First I have to say that I never dealt with a publisher myself, so all the tips I can give you are purely theoretical :-)
But if you plan something bigger, be very careful with every step. If you create a demo, be sure that everything in it works perfectly, I guess there can be nothing worse then presenting your game and it crashes after a minute or so (that is something you can do when your name is Bill Gates, but it's not recommendable for a new no-name team ;-) ) I guess the best idea is that if possible you visit the publisher at his office and take your PC/Laptop with you to demonstrate you game, on hardware you know it runs on :-) But that's of course only possible if the desired publisher isn't too far away from you.
And then, if you are lucky and a publisher shows interest, contact a lawyer to help you with all legal stuff, preferably one who knows enough about the gaming industry. Be sure that if you finally sign a contract it's waterproof. You wouldn't be the first team who got ripped off by a publisher :-(
If you work fulltime on the game that means you have to quit your jobs therefore, and so everything regarding the fincial side must be clear in the contract, like milestone payments, royalities and so, the development time, estimated release date, who is responsible for beta testing, marketing, who holds the intellectual property, publishing area (just one country or worldwide), who pays for dubbing if planned, and, what is also very important: What happens if the project blows up?
The last point is something you most likely don't want to think about, but it can surely happen, so the contract should be clear about what happens then - for example the publisher decides to drop the project, what happens to the code, graphics, music etc you already created? What happens with the payments the publisher has already done? Who holds the IP then (remember Lucasarts and Sierra) ... and so on.
There are a thousand things more to think about I bet, maybe some of the pro's here like to share some of their real knowledge with us?