Simple way to introduce letters

My son is just 2 and he often chooses this app to mess around with. He likes knowing letters, but is to young to really be able to write. He considers it a coloring app and likes to color in the letters. He repeats the letters as he hears them spoken, then draws a bit and goes on. He is getting familiar with their shapes. He can recognize about 8 or 10 letters now. I sometimes draw the letter (trace) for him to watch.
That is my only recommendation is some kind of animation showing the tracing.2

Sflolalola about Letter Tracer preschool letters writing practice