For Search Engine Optimization, I just do a few things to help the search engines find me. By no means am I an expert and my site is certainly not high ranking, but I'm thankful to have received a few new orders from it recently. Here's what I know about it:
1) Keep the pages relevant, clean and well designed.
2) Use keywords on your home page, like pens, gifts, or whatever else you're shooting for.
3) Try to get others to link to your site. This is really the most important one. Most search engines (Google in particular) place more importance on this than anything else.
As I mentioned, my site is not a great example of these things but I am slowly working on making it more search engine friendly and getting links from other relevant sites. I really need to set up a shopping cart but I honestly haven't wanted to devote much time to it lately because the occasional order that I get is almost more than I can handle timewise. Plus, these 20 hour projects sure cut into my sleep [

]. For the money, though- I think I'd do it again.