You need:
1. You (you'll draw like an obsessed inspector)
2. to draw something (something you want)
3. Pencils (or use any other tool to spend your papers)
4. Images or objects (unnecessary only for who knows how to draw those common things)
5. Essential tremor

And then happens next absurd sequences/things:
1. Watches some videos about drawing and pencils (spoiler: it's not quite useful, except techniques)
2. Draws plants and sergal parts for ~20 days
3. Pilfers little bit more pencils
4. Doesn't public the plants
5. Doesn't draw anything for 3 months
6. Draws sergals for ~4 days
7. Doesn't draw anything for 4 months
8. Draws more sergals for ~4 days
9. Doesn't draw anything for 3 months
10. Steals color pencils
11. Draws even more sergals for ~6 days
12. Done (nope)

Morale/conclusion of those sequences is... I don't how to draw and can't remember everything what happened for those months.

But now more seriously, you can learn to draw in several ways, use one theory at a time with practice (don't repeat the same practice too much). Still, I need to learn and draw a lot more and my passed process of drawing helped to draw so.
I drew not only sergals (but it doesn't matter) and, yeah, I really have an essential tremor which is usually low (it affects on my hands). And also... passed time of the process with current result is much easier than my programming learning process although I know about programming much more.