Hiya
Good luck with your new business. It's exciting isn't it!
I started mobile (although I am home based now) and the things I wish I'd has when I started are:
A portable nail table (you will get back ache trying to work on the corner of a round or square dining table and at least if you spill anything it will be on your table - try to get one with a ridge round the edge so things don't roll off)
A portable nail stool (I've been sat in some awful chairs, some too high, some way too low and at one appointment I actually nearly fainted cos I'd had my arms reaching up so far for the table cos she gave me such a low chair)
A Daylight lamp (not UV, I mean a really good light which gives out no heat cos heat will make your l&p set faster and will make your gels run) - I got mine from the Daylight Company and it's perfect. The bulb is one that doesn't hurt your eyes no matter how long you use it for (unlike, say, fluorescent light)
A case (you can pay a fortune for these) - I found an aluminium B&Q tool case was perfect, they have two sizes to choose from, even the UV light fitted in it and the little compartments in the back of the lid (which are meant for screwdrivers etc) are spot on for files and buffers etc.
From a safety point of view, don't forget to take all details when they phone to make the appointment, incl a landline phone no, tell people where you are going and when you will be back and have a mobile with you.
hth xx