Of course the percentage of the health insurance is based on what you make.
The tax, well, that could be the same. (I'm speaking of brackets)
If you have a pay stub from a job, look at the taxes taken out.
Now double it.
Then pay the large chunks every 3 months.
The good news is you have more write offs. A good tip is your car. Depreciation. That was a big saver for my wife and I last year. (Computers, gas, entertainment (some) etc.) All write off. Donations too, never been a better excuse to do it. =)