As a former drawer who pursued art as a minor (100 years ago) all I can say is practice. Look up images online (a great source) and practice duplicating what you see. Draw light construction lines to get your angles and perspective down before doing heavy line work. Shading is secondary, but important obviously. Get a variety of drawing pencils (3B, 4B, 6B, etc) and experiment how they work.
While some might say to work strictly with one medium before moving to another, such as mixing pencil with charcoal for example, I say do whatever you want. You may find where you struggle with one medium you might excel at another. I could NEVER get the hang of chalk pastels but wanted to desperately. I tried and tried but just couldn't get the mixing down to my satisfaction, so I stuck with pencils.
Just practice. Take a small 4x6 sketchbook everywhere with you. When you have time, take it out and draw what you see....a trash can, a flower, a doorknob, a leaf on the ground. Just practice.
Good luck.