Lot of people ask me "Hey I am great at HR/Finance/IT. I love solving problems, and I like working with people. would that be enough to make me a consultant?"
Er, you already are a consultant - even when you think you are not!
Goes specially for internal support functions. If you are not earning the moolah in a business then you are seeking to use indirect influence on how someone brings in the moolah - ergo, consultant.
So what are the prime skills of being a consultant or an internal service provider.
Most important - Contracting. Knowing the scope of your work and what your client expects is the biggest skill you can build. It means being truthful about your abilities and also how it makes sense for the client. People don't want scope creep to happen. Contracting needs patience, communication and assertiveness skills. It might also mean walking away from a lucrative deal - so it also needs courage. The failure of most sunk consulting projects can be traced back to this phase of the consulting engagement.
Discovery - Diagnosis calls for a skill where you play detective. Not to make your own conclusions after listening to everyone's point of view (including your own!) is a skill that tough to master. But discovery is a key skill to keep a conultant objective and not to jump to 'obvious' conclusions.
Implementation - For different kinds of consultants, implementation looks different. However the key skill in implementation is making the implementation survive your own departure. How you do that either as an external consultant or as an internal one is key. It most of the time means building skills in the client organization that might impact your recall for the same project but will add a lot of value to you.