How often do you have to do this sort of thing? Is it per client, or if you use a freelancing website, can you do it just once at the beginning? And if you can

How often do you have to do this sort of thing? Is it per client, or if you use a freelancing website, can you do it just once at the beginning? And if you can build some relationships before leaving (I'll be doing it for a while before I graduate from college), would it then be possible?