The mistake is buying a drawer unit the way you'd buy a side table, by eyeballing it in a showroom and deciding it looks about right. It isn't about right until you've measured the actual wall, the actual doorway you have to get it through, and the actual gap next to the bed or sofa where it's supposed to live. A unit that reads as modest in a big shop can swallow a third of a small bedroom once it's home.
Measure the space twice, once for the footprint and once for the clearance, because drawers need room to open fully and a unit jammed into a corner with six inches of swing room is useless no matter how nice it looks shut. Leave a little breathing room on either side rather than pushing it wall to wall, a room feels calmer with some gap around furniture than with everything flush. On quality, pull a drawer all the way out before you buy, or the day it arrives. A good one runs on proper metal runners, slides smoothly without rattling side to side, and has a joint at the corners you can see is dovetailed or at least properly glued and pinned, not just stapled through thin board. Cheap ones use plastic runners that wear out within a year and drawer bottoms that bow under the weight of actual clothes or files. Knock on the side panel, a dull thud usually means solid or good quality board, a hollow rattle means it's mostly air and veneer. For color, plain wood tones age best because they shift with the light instead of fighting it, warm in the evening lamp light, cooler and more neutral at midday. A painted finish in a muted shade, a soft gray or an off white, is forgiving too, but a bold color you love in September can feel like a decision you regret by February when the light turns flat and gray for months. On delivery day, check the drawers sit level and close flush without you needing to slam them, check the back panel isn't just thin cardboard masquerading as a backing board, and check all the feet or legs are even on your actual floor, not just the showroom's suspiciously level one.
I'd put the first one in the bedroom, where it has to earn its keep every single morning, half asleep, looking for socks. That's where bad runners and shallow drawers show themselves fastest, long before you notice anything wrong with how it looks.
