Hi,
I am a web designer and this is the most common question I get asked from my clients. Their is not one answer that server all, as the results depend on the market your web site is aimed at. If you have lots of competition then you will find it difficult, especially if one of your competitors has a big marketing budget (imagine trying to compete with eBay if you have an auction website).
As I don't know any of the details of your website, then I can only suggest the basic principles that you should use:
1. Use between 10 - 15 Keywords in your meta tags. Make sure you keep them relevant to your website.
2. Make sure you have at least 150 words on your home page, helps if you have your keywords amongst the text.
3. Quick loading pages help
4. Use proper HTML 4.01 code
5. Use ALT tags on your images.
If you want a more detailed response, drop me an email.