Ask HN: What kind of advertising have you tried that worked?

Our startup is looking to use banner advertising to help increase sales. So I have a few questions for the HN community:

1) We have ideas of what the theme of some of these banner ads will be, but we don't know the best wording that should be used. Should we get a copywriter? If so, where? How much should we expect to pay?

2) We can do the ads ourselves from a creative (art) perspective, but it may make more sense to have someone else do them for us if they are better. Where can we find a good designer for banner ads? Again, how much should we expect to pay?

3) Is there a resource online where we can gauge the potential success of these ads? We're interested in knowing what we can expect for CTR rates and/or CPC.

4) Any additional information that we should consider?

Thank you for responses ahead of time!