At the seed round, your friend should be focussed on getting whatever money they need to move forward with the business, while giving up an acceptably small part of it in return.

After those conditions are satisfied, a good relationship and shared vision with an investor is worth more than extra cash or lower dilution. These people will be your business partners until the sale, IPO, or death of your company, and so you should put almost as much care into choosing them as you do your cofounder(s).

A bidding war is fine, but huge weight should be given to the VCs themselves, and not necessarily their offers.