The important thing if you want to hire SEO company to optimize your site is to check their background first. Lots of SEO company offers such services but in the end, they can't give the customers' expectation.

The best practice of SEO is is to keep your meta tags and keywords under 20. Your keywords that you use should be the common words used on your site, the more you use a keyword the more the webcrawlers find it. And one or the best SEO tips is to have web pages and URLs on your site named after your keywords, this is a very overlooked way to get high rankings. For example if you have a keyword like "bulldozer" then you should have a a URL that looks like this, www.yoursite.com/info/bulldozer.html and the name bulldozer should be used as many times as possible on that page and other pages. My bulldozer does this, my bulldozer does that, my bulldozer is green, your bulldozer is red and sucks. Make keywords match your content as often as you can. People who sell car insurance and use keywords like "Used Cars" don't place high in search engines because the only time a keyword is used on their site it looks like this, "We insure used cars" . Just remember to be smart, it is hard to fool a web crawler. Look up keyword in Google, Yahoo, MSN, and other search engines, if you are thinking of using the word "software" and there are 76,967,534 results, change the word to somthing close or phrase it to create the lowest ammount of results...... Sorrry for the rambling but I hope this helps.