The problem with only using Twitter for customer support purposes is it reflects poorly on your online identity. Twitter's profiles will rank pretty high in Google and if everything that comes up is you looking to resolve something (even if they are legitimate concerns with companies where you weren't at fault), it comes across as a one sided use of the medium.
You also describe the usual chicken and egg problem any social medium involves. Nobody will follow you without interesting content and if you have no followers, you're less inclined to spend time posting it. Break out of that cycle by spending a limited amount of time on our tweets first. Make mistakes and figure out your voice while you don't have a bunch of followers yet. See if the 140 character limit works for you e.g.. Find value in the process of coming up with the content in the first place. If you still enjoy that, then you're well equipped for a larger following.
You also describe the usual chicken and egg problem any social medium involves. Nobody will follow you without interesting content and if you have no followers, you're less inclined to spend time posting it. Break out of that cycle by spending a limited amount of time on our tweets first. Make mistakes and figure out your voice while you don't have a bunch of followers yet. See if the 140 character limit works for you e.g.. Find value in the process of coming up with the content in the first place. If you still enjoy that, then you're well equipped for a larger following.