Holdfast said:
I learnt this by experience - I once had to go back to get a pair of trousers rehemmed because I wore boots with a higher heel than usual.
You're lucky it was only the trouser hem affected. Typically, I find other alterations to the posture as well. For example, the neck will pitch differently to accommodate the "wedge" of the shoe. As such, this can affect the placement of the collar (e.g. rise) and the grout line (what y'all refer to as "gorge").
WA said:
And, don't come in with tight pants.
Ditto. No tight pants. If that's all you own, then we'll measure you in the fitting room in your boxers or briefs.
Oh... you should know I only say these things because I have experienced something to requires I do: Please wear undergarments. Even if you plan to wear your new trousers "commando", boxers are a close facsimile to get through the measurement session.
WA said:
Some tailors like to take some measurements with a jacket on, and others think it is a waste of time.
I prefer to dispense with the jacket, unless you're being fitted for an overcoat or want to illustrate a feature you're keen on.
Generally speaking, I like to take measurements based on the foundation garment. In other words, if making a shirt, then I need measurements over the undergarment. If making a vest, then I need measurements over the shirt. If making a jacket, then I need measurements over shirt & vest, etc.