Other than google analytics and webmaster tools, I don't think there is any need for SEO tools - make sure you know html, read about what google likes and doesn't like and then apply common sense and be patient.
I think you should pick a couple of your product pages to focus on first (maybe ones with the least competition).
Decide what terms people will search on (your keywords) and make sure on those product pages your page title and description includes those terms.
Include plenty of headings in your product descriptions - make sure the product title contains your keywords and that it is the <h1> on that page. If you have a few paragraphs description, maybe put a <h2> heading above each one using similar terms to your keywords, but NOT repeating them exactly.
Make sure any images have a descriptive alt attribute.
Make sure your menu titles are as descriptive as possible (ie, say your main menu is 'jeans', rather than using 'mens' & 'womens' as submenus, use 'mens jeans', 'womens jeans')
Email marketeing can be really useful - make sure you encourage people to sign up to a mailing list, but don't ask for too much info else they won't bother. I have a quick signup box - all they need enter is their email address .