Firstly make it very clear on your ad or profile that you will only do outcalls to clean, comfortable homes and hotel rooms.
Get the full address inc house or flat number and google it before agreeing to the booking, make sure it actually exists. Is it a house or a flat? Have a Streetview look at it on Google Maps / Google Earth and have a good nose around - does it look like an area you'd feel safe being in or safe parking your car in?
Sometimes you can see a lot of detail on Streetview inc the front door. Is there junk piled up in the garden? Are there loads of old cars parked outside? Does it looks like it's under complete renovation? (I've had guys request an outcall to the property they're replastering or redecorating before now!)
If I'm in any doubt I tell them it's not an area I can go to as I have friends or family living very close and that it would be difficult to explain why I'm there if they spot me.
And finally if you decide to go ahead but something spooks you when you get there before you even knock on the door, don't go ahead with the booking. Retreat to your car and get yourself a safe distance away then call or text to cancel the booking. I've had to do that recently when all looked good online but when I got there - to a large detached bungalow - the garden was totally overgrown with high blackberry bushes and every single window had a tatty blind fully closed in the middle of the day but odd bits of rubbish could be seen piled up on the windowsills. The window alongside the front door had a ripped net curtain with dead flies stuck all over it. I ran!!!
If you step in the house and find it's a shithole, tell them it isn't the sort of place you can work comfortably in and then LEAVE.
My past experience of not having been assertive as soon as I got inside shitty properties led to me feeling really revolted and then traumatised and cross with myself afterwards for having gone ahead with it. Those clients were as filthy as their homes. Grim. No amount of money is worth losing your dignity.
I turn down about 50% of outcall requests to homes because they don't feel or look right. Hotel outcalls have never been a problem for me, but aren't requested quite as often unfortunately.
There are many other really useful posts on SAAFE about outcall safety so I won't repeat them, but it's worth doing a search on the site and reading up.