My PTR site and my other sites get very few visitors via search engines even though I use the right meta tags, content, etc. Would you recommend any ways to get my websites noticed through search engines? Recommend both free and paid services - as long as they are worth the money spent.

Promote your site! That is the key factor. How do you promote? It depends. Use Social Bookmarking sites like Digg, Twitter, Facebook, etc. Also write some unique article and submit to sites like Squidoo, Ezine, etc. You can try youtube as well.

Build SEO friendly links to your site. Submitting unique articles is a good way (twistedone mentioned it). You can submit to article directories, press releases, blogs, etc.

Some people make the mistake of overloading their meta tags and therefore might have 10 - 20 different meta keywords when really, it only benefits to have 3 - 5. It works by the law of diminishing return. Additionally, you need to make sure that your meta keywords are used in your meta description as well as in the body of the site. It is also beneficial to use bold and header tags in your body that reflect your meta keywords.

Are your websites in niches that has a lot of demand? If hardly anybody is searching for the stuff your website is about, obviously your traffic will be low.

Use Google Adwords Keyword tool to look for the most popular search keywords in your own niche, and add content about that.

Did you already find the answer to your traffic problems?