I think with any tailor, you have to be prepared with what you want, and what kind of finishes you'd like to achieve.
If you don't know what you want - soft collar, no cardboard, the kind of fit you are looking for - and the kind of detailing - back plackets, arm hole fits, you're going to get something that you don't like wearing.
Me, I bring in the shirt pattern, I specify the shirt yoke, I tell them what buttons to use - mother of pearl, fine edged, the kinds of pleats around the cuffs - and the kind of handling - wash and wear, no crease - and the fabric - silk cotton blend, lightweight.
And make time for fittings - like 1-2 weeks. I have spent money on tailors - and given them plenty of time to make amendments and alter patterns. I also order "sample" garments from them - and make it clear it is a sample garmnet.