These are some (FREE) useful links for your mission planning convenience

Checks NOTAMS here. I would suggest using the radius search function. This link give you NOTAMS for your local airfield as well as surrounding airfields and center NOTAMS.

NOTAMS

An important site to check to stay clear of any Temporary Flight Restrictions (TFRs)

TFR

Another free resource, this FAA site has a number of useful handbooks covering topics from student pilots to instrument flying. Below are a few of the more important ones.

Helicopter Flying Handbook

Pilot's Handbook of Aeronautical Knowledge (PHAK)

Instrument Procedures Handbook

Instrument Flying Handbook

Aviation Weather Handbook

Plane Sense - General Aviation Information

Risk Management Handbook

Aeronautical Information Manual

FAA Handbooks

FAA inspectors and designated pilot examiners shall conduct practical tests in compliance with these standards.

Airman Certification Standards (ACS)

FAR Part 61 Certification: Pilots, Flight Instructors, and Ground Instructors

FAR 61

FAR Part 91 General Operating and Flight Rules

FAR 91