Where to put keywords for search engines

Cant I put a whole list of text that will cause my site to be found on google in my index file so that it isn't visible on the page? I want to just list around 30 different words and phrases that people might enter into their search engine.

It's not a good idea to use text that has the same color as the background making it invisible. Search engines are hip to that and may ban you entirely. You're much better off working the keywords into the text of the page with your most important phrases inside the title tag and h1. You can also add keyword phrases to the alt attributes of your img tags and I believe most spiders will give it some weight.

If you mean your pages that are using frames you could use the noframes tag to add content that will be invisible to most users since almost everybody has a frames-capable browser. Rather than just listing the words you should use header tags like h1 there as well since it will be given greater importance. It's also a good idea to put plenty of links to your content pages in the noframes tag for spiders that have trouble indexing framed sites properly.