If you're serious about drawing, painting, sculpting, sketching, you already know it takes loads of practice if you're not one of those icky people who have a natural talent from the day they plop out.
So initally; practice drawing details. Details of the body can be f.ex. the hard ones like hands, feet, body proportions, eyes. Try putting it together into a full body that is both symmetrical and where all the parts are in right perspective to each other. Thats the tricky part
Think of it kinda like a cut-out doll. You need to know how to make the actual doll first - the silhouette, the outlines. After that you have different parts of details that you slap on there, make them fit.
To try and actually get things to look "real", draw from models (ofc doesnt have to be live models, could be a coffee cup, a photo, whatever). It's a huge difference. Draw what you see with your actual eyes. Not what your head remember, like a feeling or an idea.
When you have a model you can compare your drawing to the real thing, seeing properly where your weaknesses are - maybe you're not following the elbow line properly because you have a set idea of how an elbow looks so you actually draw it from memory rather than from reality.
If you think its hard, try starting with tracing a photo in a magazine or something. First time you trace the whole thing to gradually lessen the amount you trace compared to the amount you fill in yourself. Excellent opportunity to practice shading, how it changes the picture when using different styles & levels of intensity.
If you have an idea of a drawing, get it down on paper quickly, just enough to remember it. Include the small quirks you thought would be fun, or that you want to stand out a little extra. So basically - put your ideas to paper.
When you have your idea safely described in a probably very abstract manner, you can start working on the real thing and not having to rush it.
And maybe try use pencils (like, graphite-ish or something) and erasers instead. Helps alot when working on both shading and details, where the pen you're using here seems to bleed and makes the lines fuzzy.
Lastly i think you have a bit to go (coming from someone who struggles with stick figures though
). Your pics are kinda cartoonish and mainly outlines, which makes them flat. Shading & details does wonders
(
and yes, i know we all approach drawing in different ways. what ive stated are just how i personally look at it, how i do it when i get the urge to see if Im a da vinci after 2 years of never touching a pen. turns out i never am 
The whole "quickly scratch down a few lines and have a master piece"- kind of drawing that some people seem to be able to do, comes after you have the basics firmly attached in your spine and with your eyes closed can draw a multi-tasking dragon in lingere sipping coffee and having a puffy in front of a mac book air on top of a sky scraper in a post apocalyptic metropolis. For those of us who arent quite there yet, it requires tedious practicing, just like in 1st grade when you have those books where you're supposed to write the alphabet 743 times )