The one caveat I will say with this; if you have a situation where you feel you will need professional help, seek it. Get in touch with the IRS directly, or go through a CPA either privately or through a professional tax service. Usually I use TurboTax and file myself, however when my husband passed away, I had a CPA handle my taxes for that year, and I highly recommend anyone else in that situation to do the same.
That said, there is free tax help from the IRS.
Here is a basic link: Free Tax Help
You can also file your federal taxes for free via the IRS: Free File
For Low Income taxpayers, they have some information at this link: Low Income Taxpayer Clinics
For the State of Arizona (where I live), the Arizona Department of Revenue offers this site for free and paid tax services: