What tool to find the right keyword for my money site?

What tools are available to find the right keywords for my money sites, I have been using Google Analytics and Keyword Revealer, however, still there are too many to see exactly what keywords would turn a hit into a sale.

So my quetsion is, is there any software or script or free service to use ? Or can you suggest a method that maybe could work?

Thanks for all your input.

It's a healthy mix of keyword volume combined with a knowledge of your field. No software can interpret a list for any field, but by definition keywords that are very targeted like 'Samsung Galaxy S6 Black' are people who know what they are looking for and thus easy to convert.

We used to do a ton of keyword research for clients and the first assignment was always the client's: give us a list of brands, products, and verbs that are important in your line of work.

As for tools.. Google Keyword Tool, keywordtool.io, Longtail Pro. Anything that gets you huge volumes of keywords to sift through.

Thank you, that actually make sense... however, I know my industry very well, but still there are keywords we are ranking for in the top 3 spots but we don't get customers from it... I read endless similar scenarious on BHW about it, so no need to discuss that part... however, when we do new link building on mass, we suddenly get maybe 30 - 50 sales a day! so somehow there must be keywords that we don't see or can't see but which actually turn a visit into a sale.

What would you suggest to do in this case?

Any one else have some suggestion please?