There are many ways that you can improve probability of achieving higher search engine rankings.
The most effective way is to consider how search engines rank your pages - during 'planning' phase of developing your site.
Most issues that adversely effect search engine ranking are in-built during design, and are more difficult to remove once design is complete. Consider that most web design contracts are fulfilled when a site is posted to web, looks as intended and is functional. What happens to your site beyond this is not concern of people who designed your site, their work is complete. So if you are fortunate enough to be at 'specification' stage of planning a web site, there are a few simple things that you should do.
Ask designer specifically what steps he or she will implement to ensure your site is 'search engine friendly'. If you pre-arm yourself with a little knowledge of subject, you can easily gauge from their reaction just how well your site will be prepared for search engine submissions. You are not looking for guaranteed top 10 positions at this stage. You are looking for some evidence that designer understands basics of how search engines work, how they 'crawl' your pages, and what they do with information that they retrieve. If their reaction does not instill confidence that your site will be designed with consideration towards search engines, you have one of two choices:- go elsewhere and seek services of a company who can demonstrate reasonable knowledge of subject, or take it upon yourself to lay down basic guidelines to your designer.
The basic guidelines are:
Include all important Meta tags on each page. Keywords, Description and Title tags should be included as a minimum, and each should be set to focus on content of specific page, remaining where possible within 'theme' of site. Add 'robot instruction' tags indicating which pages should be indexed by search engines and which should not. If you have pages that detract from overall theme of site, use 'noindex', 'nofollow' tags. Avoid using 'Meta Refresh' tags that are set to automatically direct viewer to another page. If you must use 'refresh' set time to a minimum of 15 seconds. Design a navigation structure that allows search engines to crawl important content pages from home page. This can be done easily using transparent image files and setting them as hyperlinks. Remember that using Java, Flash software or 'Frames' to facilitate navigation, can often present a 'closed door' to search engines, preventing key areas of your site from being indexed. Use alt-attribute and name images descriptively. Some search engines read alt text and it can help, though marginally. Name pages using keywords. Instead of 'page2.html' use 'american-ginseng.html', if your site is about herbal products! If your site uses 'Frames' there are important techniques that go beyond scope of this report. Many search engines cannot navigate through Framed section of a site, unless Frames are prepared in a specific way. As a minimum, ensure your designer includes a detailed description about your business, products or services on 'noframes' page, and ask them to research more specific information about Frames and search engines. If site is designed using dynamic content pages as with ASP, consider designing additional pages that use static HTML. Having an 'about us' page in HTML is always a good strategy when using dynamic content pages or 'active server pages'.