How much to bid? This is an often asked question.
Ideally it should be based on the lifetime value of your customer. If you can’t calculate or rather if you are not in a position to calculate life time value of a customer then here are some thumb rules
1/3rd t0 1/2 of the Google recommended bid
1/100th of the average profit per product
1/10th the value the lead.
If you are testing or starting out use exact match only to figure out what works. Adjust the bids every 250-500 visitors at the adgroup level for the first one month.