Make a robots.txt file and I like to include a favicon because without them the robots will trigger file not found errors on your server. Be sure to configure your robots.txt correctly. Make a custom 404 page. If your site has more than just a couple of pages then also create a sitemap.xml file. It's not a bad idea to just create a sitemap anyway no matter what, it lets you define the structure of your site to the crawlers. Just search google if you don't know how to do any of that, it's very basic and you can find exact instructions within a minute when you do a search.
Other than that there isn't a lot more you can do for on-site SEO. When people ask about SEO they're always thinking of on-site SEO, but thats the easy and quick part. Just do it and get on with it.