You can skip Ebay, they take over from Immonet. Quoka, IS24 and all the classifieds providers on the web I would skip, because it somewhat resembles desperate clearing out.
The presence simply has to be right: headline, body text and photos must form a unit and must not reveal too much. The art lies in omission. You have to address the seeker! Go to my homepage (linked here in the profile) Since I am an expert in this case, I would like to see the link to Immonet – can you please send it to me? I might be able to give you a few tips – also, “nice photos” by themselves are not always what is suitable for advertising ;)