>>5956500This is actually the basics of drawing background.
Pick a perspective (or define the horizon line), for potraits, the horizon line is usually at the eye level. Once you commit to a perspective, then decide on the background elements to bring out the mood or context or composition you want. Takes quite a while to actually decide what kind of background elements to add though.
Some tips: if you're drawing outdoors. When drawing clouds, dont just randomly put them on the sky. You can use them to solidify the perspective you choose. Same goes to the flooring, buildings etc.
Think of background as to flesh out your subject. Perspective lines can be leading lines that guides the eyes towards your subject the way you wanted.
You could check out Saito Naoki's youtube channel. Even his usual 'fixing' videos tackles drawing background quite a lot.
