A quick checklist for on-page optimisation would be to ensure that your title tags contain the keywords you wish to rank for. If your company is called "Smiths Home" and you sell home improvement services, set your page title to "Home improvement Smiths Home". More keywords can be added as required but don't go over 65 characters.
Blog about your website and/or business. Post this content on relevant article websites and offer to guest blog on related websites. Ensure you have your own blog and keep it up to date.
Try to make the content as original as possible because this is what gets attention from real readers. Content is great for search engines but you need to make a distinction between your content and the content of others. Try to make it unique where possible.
Create links to your content by asking others for a mention on their blog. Also do not be stingy - link out to related blogs also! This will actually help to place your site within Google because it shows you are part of a network of like-minded websites.
For maximum efficiency why not create a network of articles and blogs which interlink effectively? This doesn't mean a load of sites that link to one another, but if you have two separate articles which relate to one another, why not link them together under "further reading"?
Some people still think that Twitter is purely a marketing tool. It's not, you have to generate content that is worthy of being read, not simply post "Home improvement services here!". Create relationships with others and these will grow into sustainable sources of traffic.