All of these suggestion are excellent points most of which took me many years to learn.

The most important for me was several years ago discovering f-stop printing. It give me a method of consistent exposure control.

At the same time it also gave me a repeatable method for consistent burning and dodging times and by adding the use of different contrast filters to my burning and dodging enabled me to really improve my printing skills.

If you are interested in learning f-stop printing you do not need a special timer. Ralph Lambrecht's Darkroom Magic website has a f-stop printing times chart available as a downloadable pdf file.

http://www.darkroomagic.com/DarkroomMagic/Darkroom.html

I printed several copies and had them laminated for use in my darkroom. I take the values off the chart and enter them into my timer.