Homer 3141,
In short, you can handle all patent preparation and filing, both provisional and non-provisional, yourself. The downside in doing this is your lack of experience. It is expensive to have a patent application properly prepared. I'll say that again- it is expensive to have a patnet application prepared. Depending on the complexity and the technology area, and your physical location, it may cost $4,000 - $20,000 for an application (or even more in extremely complex or very comprehensive cases, and in very limited circumstances, may be under $4,000).
So now you have to ask yourself "what am I getting by paying a Patent Attorney/Agent to draft my patent application myself". Essentially, a viable patent application that hopefully matures, someday, into a viable patent.
There are two sides of a patent application document- The technology side, and the 'legal' side. You may very-well understand the technology side, but if you don't understand the legal requirements and ramifications of wording in a patent application and the 'Claims' section, you may (and very likely will) forfeit your invention to the public.
The reason it is so expensive to have a patent application prepared is because it is not easy work. In addition to being able to understand your invention sufficiently to put it into Figures and writing, a patent attorney must be current on the current state of the law. The way a patent application is worded can strongly affect the coverage of any patent that issues, to the effect that a poorly drafted patent can easily be designed-around, or invalidated (especially if it doesn't meet Best Mode, Enablement and Written Description requirements, Disclosure requirements, etc...)- Invalidated meaning that you would have NO patent rights whatsoever.
It takes 2-3 years to properly train a patent attorney/agent in the legal requirements of a patent application, dealings before the Patent and Trademark Office, proper wording and "how to" drafting of the Claims Section (that defines your invention). This is 2-3 years at 40-50 hour or more work weeks, 50 weeks a year. And there are a whole slew of querries before you even get to the the patent drafting stage, such as the degree of secrecy you've exercised with the invention, if/when you've publically disclosed the invention (I guess the same as secrecy), who is ok to disclose the invention to outside of a written Non-disclosure agreement, whether you've used the invention in a commercial sense (even if kept secret), whether you've used the invention in the public (outside your home or some development lab), whether you've offered for sale or sold your invention - all of which could affect your rights to your invention.
I've never come across an independent non-patent-attorney inventor that came close to adequately preparing their patent application. I've had many come into my office, after attempting to prosecute their own invention, with several goings back and forth with the US PAtent and Trademark Office, and having already paid the filing fee, several late fees and extensions of time fees, and were presented with a communication from the patent office saying that they were non-responsive and that their application his in danger of being abandoned. They had already paid $2,000 - $3,000 in fees, and I'm sure frustration in dealing with the Patent Office, simply because they were ill-equipped to perform that task. And, when they met with me, I had to tell them that the quality of the application prepared, likely wouldn't protect them even remotely from anyone that wanted to "steal" their invention. In some limited circumstances, I was able to tell them that the disclosure they made could be partially salvageable, but because the amount of work and effort in salvaging the application it would cost essentially the same as if they had come to me in the first instance. In other cases, I had to tell them that there was nothing I could do for them,that likely their invention as was publically disclosed was in effect donated to the public and no longer protectable by patent. And believe it or not, it breaks my heart to have to deliver bad news to these people who are so excited and enthusiastic about their invention.
It wasn't uncommon for them to tell me that they've kept their invention secret, but in the next sentence mention that they were having a local shop prepare a prototype, but there wasn't any agreement to keep the invention secret, or how
they kept the invention secret but that they received a quote from some local shop that <some number of units> could be produced for <some dolar amount> again, withput any nondisclosure agreement in place.
Do yourself a favor, and meet with a patent attorney/agent. It's really a matter of being penny-wise but dollar foolish if you don't.
Best of Luck