How does the multi-entry tourist visa (METV) work in Thailand and do I need to show proof of onward travel?

METV, Obtained in your home country, show employment or business ownership and the equivalent of 7000 USD in a bank account

The way to get the most out of that visa is to:

get it as close to when you're gonna travel to thailand because the 6 months starts from the day they issue the visa at the consulate.

Then fly in get 60 days

when that's up, border-bounce to get 60 more

when that's up border bounce to get 60 more

just before the "enter before date" on the visa itself border bounce on final time to get the last 60 day entry (giving you almost 240 days) and then extend that last entry by 30 days at the immigration office for 1900 baht taking to really close to 270 days..

When you fly in on that visa the immigration people at passport control won't care if you have proof of onward travel or not.

nope, you can't stay 6 months without leaving the country.

It means the visa will be valid for 6 months from the date it's issued, and when you come into thailand you'll get stamped in for 60 days.

At the end of that 60 days stamp out of thailand, stamp in&out of another country and stamp back into thailand to get another 60 day stamp.

You do that for the validity of the visa itself (6 months). Most people who time the border-bounces <- (where you get stamped in for another 60 days) right can wring about 9 months of time in thailand out of that visa..