It kinda also depends on what your client is specifically looking for...if they want that logo that looks like crap but is cheaper than that's their loss lol. When you get a client...do they give you their ideas on how they want it and you do it based on those ideas or does the client pretty much leave everything up to you? Maybe, if you haven't already done so, ask them for their ideas first then do your projects based on those since it seems difficult to please some clients.
Sorry to say but if you can't even think of an answer to this question yourself you probably shouldn't even bother trying to get into freelance designing, even on a low end site like 99designs.com. Just saying.