Remember this is for amateurs like me...
1) For your first shoot I would advise not to think about it too much - just go with the flow. Obviously prepare as much as you want to, but do it just to get a feel of the whole process.
2) If you're strapped for cash, start talking to people. Approach unis and colleges. There may be models, photographers, make-up artists that want to do the same thing as you (start a portfolio) in which case you're doing each other a favour and won't need to exchange any cash!
3) Look at magazines, clothes, music, shops etc for inspiration. See how it's been done before.
4) Start the shoot early in the morning so if time escapes you (which it more than likely will) you won't feel too pressured.
5) Choose the strongest images when selecting which pictures to use for your portfolio, or whatever they're for - even if it means just using one. It's easy to like the whole lot when you've never done it before - they all look pretty!