Very simple tips
Ensure your website is always updated. Search engines will mark a website down for out of date information.
This is an easy way to keep websites updated and active. Having a news page/section ensures you will always have something new to put onto the website.
The number of links will help your website increase its search engine rating. However, links must be relevant. A website selling music downloads that have links for cafe's will be marked down because it shows that links are being used only for SEO puposes.
Websites need to have traffic; people looking at it. One of the best ways of doing this is PPC or pay-per-click. Paying for your website to show at the top of page 1 on a search engine is often the best way of doing this and it will help the website show higher up on natural search results.
Not only is it important to have people going to your site but also make sure people are looking at the site and clicking throgh various pages. Also make sure that your website is HTML based otherwise search engines cannot recognise click throughs.