Wholesales: Offer Price to a seller

This is what I want to know when presenting an offer to a seller should offer 40%-70% of the ASKING PRICE or VALUE PRICE (Homes worth) ?

And what would be a good percentage to start off at?

Thank you all again who responds. Please be clear in your answer so that it is very understandable basically lamen's terms lolz :lol:

I appreciate everyone's responses because it helps me and other curious minds to become better and knowledgeable as a real estate investor and business owners.