So I'm trying to teach myself how to draw.
Like, from the bottom up.
Any tips for a guy who literally can't draw a straight line properly?
Tip one: Rulers are for straight lines.
It largely depends on what you want to draw and what style you want to strive for. My advice would be to get yourself some good tutorials and follow along with the basics. Also, books. I definitely recommend How to Draw Comics the Marvel Way. I've used it to teach elementary-age kids, and I've had my copy since elementary school.
Start simple and work your way up. The aforementioned book uses simplified anatomy, and you learn to build people out of various shapes. Once you have a feel for basic structure, then start delving into the anatomy. Anatomy can otherwise be very, very daunting and outright confusing if you don't already have a basic concept on how the body is put together.
So, yeah, start simple. Study, practice, study, practice, study, and practice, and study, and practice. Draw from life, from pictures, find work by your favorite artist and draw it. This will help you develop the fine motor control and teach your brain how to view various images and compositions in order to draw them, usually by breaking them down mentally into their constitute parts.