Sign up to one of stox/cardrunners/deucescracked (DC is best of these IMO). It's like $200-$500/year or thereabouts and is well worth the money. As with coaches, you probably need to be playing midstakes since to get a good coach you'll be looking at >$150/hr and you need to be making enough money to make it worthwhile.
Personally, i don't think coaches are necessary if you are a pretty intelligent person. There is a lot of info out there that is free (forums, etc.), alot of useful information in video sites, and the rest comes down to synthesizing that information and applying it to your own game. It is also very very important to work on tilt/emotional control, as that will enable you to see game flow for what it is - a failure to do this tends to result in dumb play that varies from what you yourself would consider rational play in a proper mind set, ie. if you can't control tilt/make rational decisions, then all the poker training in the world isn't going to help you once you let your emotions get the better of you and abandon "optimal" play. The gist of what i am saying in this paragraph is that many players have learnt correct counterstrategies/play, etc. but are unable to adequately apply that knowledge to a game situation because they let emotion get the best of them or start to misread game flow/metagame, etc. Ultimately a teacher can only teach so much. A "good student" will probably learn more on their own (not own their own per se, but from all information that is not directly related to coaching) than a bad student would learn will the top teachers teaching them.
It also depends what your goal is with poker. If you intend to make this your career or whatever, then investing with a coach will be more likely to pay dividends as opposed to playing casually.