SysAdmin1138 is a user on octodon.social. You can follow them or interact with them if you have an account anywhere in the fediverse.
If you don't, you can sign up here.
@brook Trying things on is the best bet. That said, if you're buying online, the size-guide is useful for figuring out range.
If you want to weed out pants in person, I recommend a string method. Get a pair of M pants that fit you in the waist, and lay 'em on the bed. Run a string across the waistband, and tie knots where they meet the pants. Use that when shopping to pre-check pants, and you'll cut down your returns (or visits to changing-rooms).
@brook For shirts online...
If it's fitted, I size to waist.
If it's not, I size to bust/chest.
If I size to shoulders, it's too big everywhere.