Search Engine Optimisation (SEO)

I have been looking into Search Engine Optimisation (SEO) a little recently for my site and here are some great tips to get you going:

1. Metadata: Get your metadata included and up to date including keywords, title, description, last updated etc. Google doesn't use keywords anymore because they have been abused by sites, but other search engines still do, but they do still use the title and description metadata.
2. Get inbound links to your site: Get as many inbound links to your site as possible, there are a number of ways to do this including registering on free directories for your industry (search for what you are selling or providing along with terms such as "submit url", "add site" etc), do a similar search for guestbooks, forums etc in your industry and get links to your site on their as well (put your url in your signature for your forum/guestbook posts then you can get your link onto your posts without upsetting websites by blatant free advertising), the biggest win for links is on non forum/directory sites (i.e. other companies, organisations etc) but make sure people linking to your site contain relevant information or the Search Engines could take points off you for cheating.
3. Put your titles in H1 tags: Google uses these more than keywords now, but don't put everything on your page in H1 tags, have 1 or 2 H1s and then put sub titles in H2, H3 etc or you could lose points for abusing the system.
4. Use your images well: Don't have images on your site called things like 1lf45.jpg or even users.jpg, get your keywords into your image names, so if you are a company selling caravans in cornwall, don't call your logo logo.jpg, call it "caravans-cornwall-west-country-logo.jpg" if you have 50 images around your site you can get your keywords in there an extra 50 times! Also, remember the ALT tag on your images, again get your keywords in there and you can really improve your keyword density, sometimes by up to hundreds of times!!
5. Place keywords wisely: Try to keep keyword heavy information in the top 25% and bottom 10% of your page. These are the areas focused on by search engines.
6. Have a link to your sitemap on your homepage: Have a sitemap.xml page describing all the pages and their location in your site and have a link to it both at the top and bottom of your home page.
7. Use free tools: Google provide free tools, such as their Analytics tool and also their Webmaster tool, which lets you register your sitemap with Google and see when Google last visited you and other information regarding any problems Google has with searching your site. Also, by using these tools, you are letting Google know you exist and declaring your allegiance to Google, which can't exactly lose you points with them.
8. Submit your URL to Search Engines: Most search engines have a link to submit your site to them. Do this on as many search engines as you can, certainly all the main ones like Google, Yahoo, Alta Vista, AOL etc and repeat your submission every couple of months.
9. Register on DMOZ: Register your site at http://www.dmoz.org/ which wins you favour at Google at the minute.
10. Validate your pages: If you have time, it's worth validating your pages at http://www.w3c.org/ and getting their validated logos on your site. This could take time, but is a big win with Google.

All these things obviously take time, give yourself at least a couple of months to get through them all. Search Engine Optimisation is a long term process, sometimes you cannot tell for weeks or months if changes you make to your site have a positive or negative affect on your ranking in search engines.

Your hard work and patience will pay off in the long term though.