Without going into too much detail about what I do I will pass along these tidbits of knowledge.
If you arent detail oriented, or if you are a procrastinator forget it.
It only takes a couple of weeks of putting off reconciling your bank statements to FUBAR your whole accounting system. It only takes 1 or 2 accounts slipping through unpaid to put you in a huge cash bind.
You have to be decisive, and willing to see through your mistakes to the bitter end. There are days that I have had to make a decision that could cost my company 10's of thousands of dollars, before I had a cup of coffee in the morning.
Even though you may get days off, there is almost always something that you could be doing, this is how workaholics are born. You must find the delicate balance between being your own boss and actually having a life.
You should know accounting inside out, outsourcing your accounting is relatively dangerous (IMHO) It is quite easy for someone who knows acocunting to pilfer money from you. In the end you are responsible for bad bookkeeping.
You will grow to despise taxes and government intervention. Hardly a day goes by that we dont receive some sort of paperwork from the IRS. Quarterly taxes are a bitch to pay, and always seem like a huge burden regardless of how well you think you have planned for the event. If you have employees, you can 10 fold this hassle.
In the end you are the boss, there is nobody to complain about except yourself, you are the master of your own destiny. That is both good and bad. Your business can run like a well oiled machine, or you can get so mired down in the day to day details, that it becomes a huge quagmire that comsumes every waking moment of your life.
It can be a very rewarding experience, or it can be a huge mistake. The freedom that it provides are unmeasureable, by the same token, the pitfalls also are unmeasureable.