Give a limited time offer and say it. But this space will only get more cluttered and more expensive. You can't expect to convert most surfers to customers in a single clickstream. You can convert more surfers into customers by giving the prospective customer more chances to convert. Don't forget that strong offers get strong results.
Offers make even the strongest brands perform.
Strong graphic treatments get attention. One big visual is generally better than two little ones. People are more likely to do something if you ask them in a clear, uncluttered way. In a cluttered world, people often appreciate fewer options. Every page you're on has a lot of competition for the surfers attention.