How to evaluate a potential business partnership?  

Recently, I connected with a potential client / partner who seems ideal.

He  is an online entrepreneur who has sold his business in the last couple  of years and then purchased 12 physical service shops that are in the  same space as his previous businesses.

He  has a product idea for this niche space and apparently buy in from the  industry as well as contacts due to his previous businesses.

He  is looking to partner with a designer / engineer (me) to make this  product a reality and is wondering about my risk level (read equity).

What are the questions that I should be asking him or what research should I be doing for a better idea for how to proceed?

I think my ideal would be to still receive some money, but also have equity.