What state are you in? If your state has an income tax then you will need to set that aside and can get the tax tables from them either online or have them send them to you. Same for federal taxes, you will need to use the charts based on how often you get paid and set that aside as well. This is, all after you have decided how many (withholding allowances) you will have, there is a worksheet for that as well. (for example I have 4 kids and a wife and myself and my allowance is 7) There is also a self employment tax of 15.3 percent so you will have to hold that out as well. don't forget your liability insurance as well, I break that down and withhold it as well monthly. also if you are paying work comp then you need to pay that as well unless you plan to go work comp exempt. Write down all your expenses and deductables (would be really good to visit with an accountant so you can get an idea of what you are entitled)
basically all the fed info is on the IRS website and there is a PDF you can download. Your state should have the other stuff as well on there website.
I would recommend that you get yourself a business name and register that as well, some states require you to have that to get work comp exempt etc...
dont worry about a FEIN # at this point wasted money in my opinion, just use your social security number.
As far as setting the money aside to pay taxes, you are supposed to pay quarterly after you get an idea of how much you will be making consistantly, usually after the first year you will know that and there should be no fine for not paying quarterlies the first year.
Not an accountant so someone can feel free to correct me, just what I had to go through.
Good Luck.
Brian