How I do my taxes: An overview of the weird, homegrown system I use to prepare and file my own taxes.
Free File Fillable Forms: Free E-filing for federal taxes based on filling out tax forms directly, rather than the "interview" style used by most tax software. I personally find this easiest, for reasons I explain my writeup of how I prepare my taxes.
IRS site search: Good for looking up forms. Note that if you're looking for a specific form name, you can often just type it into a site url, for example irs.gov/ScheduleB or irs.gov/Form1040.