Big E, I have had some experience using Patent Agents and I have to say they were not good experiences, not one. To be professional at Patent writing, you need to have an almost Savant-like ability with things Mechanical and Electronic. If you do not have this as a basis, then you will be of little value to someone wanting to Patent a design. If they are wanting to Patent a medicine or chemical process, then it gets even more difficult for you.
Writing Patents is not just writing up what the client provides, you have to able to think ahead and about what it being described. If you have not spent your youth tearing apart and successfully rebuilding car engines etc, then this may not be for you.
The caveat is of course, if you are contemplating being a Patent Troll, then pretty much any experience with the seedier side of life will be adequate.
I suspect on that latter subject that the days of Patent Trolls are fast coming to a close as the Courts look at the abuses and rabid performances to date by a few less than stellar folk.