Yep, a singing coach is massively important. In my experience the basics of voice training hold true for rock, metal, pop, blues, folk and classical singing. The differences between them are how you use the voice after you have mastered the basics.
The first thing to do is to find a coach that will teach you how to find your chest voice, your head voice and how to find a mix between the two. If they don't know what you are talking about, then they probably don't know the latest way of teaching singing.
The basics should involve exercises that concentrate on the above, and through repitition you develop the muscles around your larinx that give you the control of pitch and your unique tone.
BTW, in my reading on the subject only about 4 percent of people are absolutely tone deaf and will never be able to sing in tune. The rest of us can do it through practice and repition using the correct techniques.
Let me refer you to the programme that I'm currently working on. I bought Brett Manning's 'Singing Success' CD tutorial but you can also do his course online. I would much rather have had one-on-one tution and the reason I went this route is because I could not find a single coach here who follows this approach.
I'm not essentially a vocal coach but some of my pupils want to play guitar and sing, and their singing is often so abysmal that I also include voice coaching using similar techniques to Brett's with great results.
http://www.singingsuccess.com/
BTW he coaches Hayley Williams of Paramore as well as Keith Urban, amongst others.
