Good Site Design for Better Crawling

Some search engines see the web the way someone using a very old browser might. They may not read image maps. They may not read frames. You need to anticipate these problems, or a search engine may not index any or all of your web pages.
Create HTML Pages and links
Often, designers create only image map links from the home page to inside pages. A search engine that can't follow these links won't be able to get "inside" the site. Unfortunately, the most descriptive, relevant pages are often inside pages rather than the home page.
Solve this problem by adding some HTML hyperlinks to the home page that lead to major inside pages or sections of your web site. This is something that will help some of your human visitors, also. Put these hyperlinks down at the bottom of the page. The search engine will find and follow them.
Also consider creating a site map page with text links to every page within your site. You can submit this page, which will help the search engines locate pages within your web site.
Finally, be sure you do a good job of linking internally between your pages. If you naturally point to different pages from within your site, you increase the odds that search engines will follow links and find more of your web site.
Images
Spiders don't read images but they do read their textual descriptions in the tag, so if you have images on your page, fill in the tag with some keywords about them.
Always insert you images in CSS. It is a good and effective way from the SEO point of view. It takes lesser space then other coding technique.

Avoid Frames
Some of the major search engines cannot follow frame links. Make sure there is an alternative method for them to enter and index your site, either through meta tags or smart design. For more information, see the tips on using frames.
Dynamic Doorblocks
Are you generating pages via CGI or database-delivery? Expect that some of the search engines won't be able to index them. Consider creating static pages whenever possible, perhaps using the database to update the pages, not to generate them on the fly. Also, avoid symbols in your URLs, especially the ? symbol. Search engines tend to choke on it.
Page Size
Web site designers, webmasters and site owners are highly concentrated in attracting and deriving visitors to the web site and make conversion herefore, designers will add lots of high quality images, flash presentations and much more. Page size won’t be concerned at this place. Bigger page size takes much time to load in the browser where as visitors won’t wait till that time. Moreover search engines can store only page information’s within definite size in their database. This problem can be solved by reducing the page size below 300k and loads within 30seconds in all the browsers.
Flash Home Page
Fortunately this epidemic disease seems to have come to an end. Having a Flash home page (and sometimes whole sections of your site) and no HTML version, is a SEO suicide.