Hi Rupert,
First your questions are a little too vague, first my question for the 2 sites you and your brother have already created, have you studied how to use title , keyword, and description tags. Have you made your sites with clean html the cleaner the better, and how focused our your sites how original is your content, what are you doing to promote these sites. this would help me and others give you our opinion, I believe that if your current 2 sites have well written ORIGINAL and FOCUSED content that you should really dedicate more time to getting links to your site from other sites so that search engines will start picking up your content.
Here are a few items that help in SEO
Focused Sites
Keywords in domain
Keywords in Page for example
www.yoursite.com/keywords.html
Correct use of tags
Error free Pages
Fast loading pages
pages shouldn't be to big 127kbs is big but not to big for a page
GET LINKS TO THE SITE FROM OTHER SITES OF RELATED SUBJECT
submit your site to directories that have your subject perferably ones that have some decent PR
don't over saturate your keywords in your pages but make sure to use them a few times and use correct <h1> <b> <strong> tags
set up a site map and link to your pages from your own site and with in your content
Give it time sites don't usually get picked up and hardley ever get high ranks at the beginning it takes time patient and alot of hard work