Don't pussy foot around, go for the FS first time, just make sure it's an experienced escort(with excellent reviews) who's newbie friendly. We were all newbs at one time.

It depends on your area and on the lady. As for area, you want to fit in and not stick out as you walk into the hotel or wherever you are going to see her. If everyone wears suits in that area don't show up in surf shorts . LOL. On the other hand if you are at a beach resort and everyone is in surf shorts, don't show up in a suit. As to the ladies some will care more than others how you dress. Some will even treat you better if you dress nice. But for most, your idea should be fine. Be well groomed and don't be sloppy. If jeans are what you normally wear and you are comfortable in them, just make sure they are nice clean jeans without holes and stains. You already know the main thing is cleanliness and hygiene, and treating the lady with respect.

Your location and time of year.  I"m in Florida, so I dress Florida appropriate, depending on the time of year.  In more wintry climates, again dress for the weather, but clean and neat.  If you are just going to her incall, it's not necessary to dress for the office.  

If you are going out to dinner, of course, dressing a step up from very casual might be in order depending on the restaurant you're going to.

Grooming is top priority.  Be clean, ALL OVER your body, esp the buttcrack, yeah I said buttcrack.  Many ladies prefer a guy that shaves the pubic area, the boys down there tend to get better attention.  If you can't shave do to homelife, be sure it's squeaky clean down there.  It's not necessary to be clean shaven on the face, but stubble tends to met with disfavor, esp if you want to have some dinner at the Y.  Many ladies do not object to beards or staches, but if they are prickly, she might not be as receptive.

Do your research on her preferences on grooming, if you can find them.  Above all, do your research on all aspects of her, as has been indicated in previous posts.

Swim

driving me (im not a good driver in big cities..lol) to an outcall appt....helps to blend in.