6. Education - You can deduct employee training costs, and since you are an employee of yourself you can deduct your training costs. So if you buy a new book on server administration, or if you subscribe to a webmaster information content site, these things are deductible.
7. Home Office - If you work from your home or apartment you can deduct that as well. Not your whole house to be sure, but a percentage of its value or a percentage of your rent. You will also be able to deduct a portion of your utility costs, so be sure to save a record of those. You should figure out in square feet exactly what percentage of your home you use for business.
What you can deduct is not limited to expenses accrued only during the previous year. If you bought a monitor 3 years ago and still use it but never deducted it, you can deduct it now.
So, now that you know what can be deducted, you need to keep track of your expenses. I find a simple spreadsheet or database will work fine, but if you like you can buy one of the more expensive software suites. You should of course save all receipts or invoices related to the expenses. One easy way to do this is to get a business credit or check card and put all expenses on that. Then, not only will you have the receipt, but you'll also have the card statement listing the expenses. To get a business bank account you usually need to either have at least a DBA (doing business as) or higher (such as an LLC or S-Corp) and an EIN (employer identification number, you get it from the IRS). Once you have a business bank account you'll be able to cash checks made out to your business and get a business check or credit card.
Income isn't nearly as complicated as expenses but is at least one thing you should know. It is your responsibility to keep track of how much you make. At the very least you should record each check you receive in a database or spreadsheet before you cash it. If you are relying on your income sources to send you a 1099 you may be in for a surprise, as they sometimes forget or the forms may be lost in the mail, or if you have a corporation they don't need to send you one.
Your taxes will be due on April 15th just like everyone else, but you will also have to pay quarterly taxes. Quarterly taxes can be paid either by estimating how much you've earned in the current quarter, or by using your total tax liability from the previous year and dividing it by 4. If you have a question about quarterly taxes you should ask your accountant. Additionally you will need to send anyone that you paid more than $600 a 1099 form by January 31st for all income earned in the previous year.