Specific things

Meishi or Business Cards

Since 2017 (?) At Home has been releasing Meishi or Business Cards for their Premium maids. These are special collectible cards that feature the maid's photo and some personal information.
They can be obtained when buying a course (drink, food or dessert) that includes a cheki and chose to do one with that premium maid. When she comes back to bring your signed cheki she will also give you her meishi card. Sometimes you may need to remind them to give it to you. When the maid signs your cheki on the spot on stage, she will give it you there (or remind her to give it to you).
Note however that it is possible she doesn't have any because she is either out of cards or that she didn't bring them (usually during a cosplay event), sometimes she may need to go get them from the back.
Also, meishi tend to be renewed periodically (usually yearly), so you might see different versions over time.

Another special case are the Akiba Broadway maids, they have also have their own meishi cards that can be obtained by doing a checki with that maid. For an Akibro meishi it is not necessary to order a course, you can just do a cheki with her and she will give you the card along with the signed cheki.
Since some of the Akibro maids are premium maids, this means that they have 2 different cards and they will usually give them both.

Maids in Meidoin also had their own meishi cards, but those are no longer available since Meidoin has ended.

Serving schedules

Maids post their serving schedule twice a month on X. While premium maids will post them stating from which to which hour they will be there, regular maids post them using specific description. These description do correspond to specific times but that may not be obvious right away so I will explain them here.
Since premium maids don't have a fixed location, they only announce the location on the day they will be serving.

Japanese	English	Time	Explanation
オープン	Open	10:00 tor 11:00	Time when the cafe opens, depends on the day. Usually 11h on weekdays, 10h on weekends.
おひるまえ	Before noon	11:00	An hour before noon.
おひる / 真上	Noon	12:00	Noon, 'ma-ue' meaning just above (the hour hand on a clock face is in the up direction)
おひるあと	After noon	13:00	An hour after noon.
おやつまえ	Before snack time	14:00	An hour before snack time.
おやつ	Snack time	15:00	Snack time in Japan.
おやつあと	After snack time	16:00	An hour after snack time.
真下まえ	Before evening	17:00	An hour before dinner timer.
真下	Evening	18:00	Dinner time, 'ma-shita' meaning just under (the hour hand on a clock face is in the down direction).
真下あと	After evening	19:00	An hour after dinner time.
雪だるま	Snowman	20:00	This might the biggest mystery of all, what does a snowman have to do with 20h? Well 20h is 8 o'clock and the number 8 looks somewhat like a snowman with a smaller circle on top of a bigger circle.
ラスト前	Before last	21:00	Just before closing time.
ラスト	Last	22:00	All cafe close at 22h, so the maid will stay until closing time.