Ways not to lock your bike

It wasn't near the Gare du Nord at all - and I'm pretty sure I saw other bikes chained up to other lamposts/'street furniture'.

Maybe it varies by arrondissement...
I park my scooter on the big pavement thing when I pick people up. Don't think the rules vary with arrondissement. If you avoid stationnement genant (blocking the pavement, being in the way etc) then you're usually fine.