According to wikipedia, involute gears are the most commonly used system of gearing today. They are named as they are because the profile of the tooth follows the curve of an involute of a circle.
Involute gears are useful because they transfer energy between cogs with a constant velocity throughout the meshing, and because they increase tolerance in gear spacing.
This youtube video gives a clear and simple explanation of the failings of square-tooth gears compared to involute gears as well as some miscellaneous gear fundamentals.
Don't guess the numbers for your involute gear, take a look at some resources others have put together to document formulas and methods of construction.
This engineers edge page has a great set of depictions of the various characteristics of an involute gear and their associated formulae.
There are a good handful of youtube videos describing construction processes which can be used to create involute gears. I found this video relatively clear and used it for inspiration in my own crude OpenSCAD library.
If you take a look around in that repo you will also find a composed assembly of these involute gears, both in blender format, and in a ready-to-print STL.