Decent beginner camera for hobby portraiture?

Hello camera-fiends!
-I have no experience using complex cameras
-I want to start taking photos of people (outdoors, urban, nightclubs etc) as a hobby
-Can you recommend a good starting camera?
-Needs to be able to take decent quality photos in a range of lights
-I've been pondering mirrorless due to reduced bulk, but open to suggestions for new or second-hand cameras
-Cheaper the better, as this is a new hobby!

Thanks :)