Teach me about buying a used bike

[ecr959]

Hello everybody

I want to learn from the veterans in this forum, the Do's and Don'ts of buying a used bike. From an individual.
For example: I show up at the guys house, I like the bike, test ride it maybe, so I pay money.
How do I ride it home without plates ?
Will he allow me to use his plates until I get my own plates ? IF not, then how can I take it home ?
I see alot of ads (Craiglist, for example) where the owner says "bring cash and take it with you"
Are they assuming that I will bring a truck and load the bike on it ?

Here's a good question: Can I bring the plates from my GZ and put it on this bike ? Just to ride it home ?
How have you guys handled sales of used bikes ?

I need to learn these things, because I want to shop around for a bigger bike, maybe in 6 months.