How much should first bid be?

[thumper]

:) Hello and greetings from a first-time poster. I want to depart from Denver (or Colorado Springs, preferably) and arrive in Spokane May 7, and return May 11. Any tips on opening bid, and whether to use Hotwire or Priceline? Is there a standard opening bid percentage of posted price, say 60 or 75%, etc.? Cheapest posted rate is a Denver departure, nonstop on Frontier for $227 each.

:)

Thanks.