Got some old rusted (partly) iron tools from a friend or your grandparents? These these are usually of higher quality and strength then the basic tools from a local shop. So don't be to quick to put the tools in the trash bin.
Using a steel brush and a file (the workshop tool to treat wood and metal) you can restore the the tools to former glory.
Photo 1: The beginning
Photo 2: The end result
Step 1: Tools and fixation
Find yourself a drill with a high rpm, and don't use a cordless drill since you will be switching batteries every 5 minutes.
Be sure to use a proper clamp to securely fixate the rusted tool! You are using a steel brush at high speed and don't want to shoot into your clothing or other surrounding objects because the rusted tool was not secure enough.
If possible, use a drill with a second handle, this helps positioning and reduces the risk of damaging your own hands.