Sure, the first goal you want to shoot for is the automatic food resupply. It's been awhile so I can't remember if this is unlocked after first special person visit or through one of the maids upgrades - the answer should be somewhere in thread.
If you're new, make sure you expand the action menus so you can see the hotkeys on the bottom and top of screen, that way, putting a maid at a location or bringing her to a customer is as easy as pressing 1/2/3 -> click. Same with food items, you'll be able to see the hotkeys and when a customer orders, quickly click q/w/e/r/t/y/u/i etc and the customer.
You need to have enough food in stock to sell it to customers, at the end of the day, go to the "supply room", and increase the quantities by a bit for what you can afford - I'd focus on the cheap stuff early like having 10+ coffee and hotdogs and lattes etc, you wont have the money for 10+ pies etc. Once you unlock the auto resupply, I work towards being able to have a constant supply of 20 items of everything in stock.
For the girls other skills, I haven't minmaxed it much, but both the "Care" level and "take out" level will increase profits, make sure you're using them up each day. The phone number is probably the least important (for money making, it's important for story progression though). Figure out which customers are good tippers and which are bad, the bad tippers that sit down forever you can choose to just ignore and not serve, the popularity hit to the cafe usually is preferably to them taking up a spot from more valuable customers.
