Have a look at http://www.robotwars101.orghttp://www.robotwars101.org and search its forum for the best advice.

There is also http://www.bobblebot.co.ukhttp://www.bobblebot.co.uk (my site) and http://www.antweight.co.ukhttp://www.antweight.co.uk

I could repeat what is already on those sites, but they probably explain things better than I can

We have recently started an Antweight Wiki at
http://www.anweights.co.ukhttp://www.anweights.co.uk run by myself, however there is not much information on there yet, so it would only be of limited use.

Good luck!

Mike
http://www.bobblebot.co.ukhttp://www.bobblebot.co.uk
http://www.antweights.co.ukhttp://www.antweights.co.uk