The best you can do.....

in a hotel environment is

Stay someplace with a large busy lobby

don't plan on high volume in a hotel

give specific directions to the gentlemen about waiting in their car til you give them the room number, how to find the elevators, turns to take etc.

scope out alternate entrances that may be unlocked on the outside for alternate traffic patterns

have visit protocols - tell your clients to wear business casual, carry a briefcase or file case, do not bring paper bags or gifts...

tip the staff well

Don't ask for extra towels - lift them from the maid's cart when she's not looking...

Any hotel with a decent security staff knows what is going on on their property. There are almost always cameras you do not know about as well.

However they will leave you to it if you do not inconvenience their other guests by making too much noise or being too obvious

biz is biz after all - you are renting a room and exposing potential new clients to their property....

as long as the property you are using does not have management that cooperates with LE as a matter of policy you are good.

AVOID the 'suites' type places especially those with a door that opens directly to daylight

Avoid the cheapo chain "hotels" - they tend to be more likely to be on LE radar

Oh!  and you will find that you will do better in all of these regards with clients whom you attract from review sites or verification sites as they tend to be more experienced and know how to act in and navigate hotels...

When he calls from his car...  tell him the lobby layout.  Like through the lobby, first left, elevator on your right.  

Cameras are not an issue, just tell them to walk straight past the desk.  

If guys don't mind, you could suggest parting away from the front entrance.  I often take the stairs down & exit through a key card entrance...  I'm going out not in & going down 3 flights is no big deal even with my cane.  

I've had ladies get rooms near an side / rear door & let me in.  

++ change rooms very often.  

High volume is never a good idea.
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You are attracting more attention from curious eyes working out of an apartment day-in and day-out than you ever will in a large busy hotel.

Cameras are not really an issue since there is rarely someone sitting there watching them.  They are more archival and guys who see ladies in hotels know that the cameras will be there.  When a guy calls for the room number you can leave the door unlatched for him so that he doesn't have to knock and stand in the lobby (only a good idea if it's a regular).  Also, limit your appointments and spread them out a bit. Maid traffic is heavy up until check-in time so you don't want a stream of guys in and out of your room in the late morning to early afternoon.