SEO keywords

I received an email from PPH saying that you were offering to suggest a number of keywords [that presumably could help me get to the top of Google].

I have just finished an ebook whose title includes a mathematical equation and the words : The Formula for Happiness

The people interested in my book would be people looking to get rid of negativity on their lives, become more positive, have more intuition, more 'bounce back' ability, perhaps those interested in the Law of Attraction etc.

Can you tell me how you operate and exactly what I would get for £25. I know it may not be much but it has taken me 2 years to write my book- 2 years with no income so my money has to be well spent:)

Marjorie Green