I'm a local so I will answer you from my point of view (which can be different from the other locals thought...)

I always appreciate when people coming from other countries ask for some help (not always easy to answer with my level of english, but there's always a way to do it)

So you can ask for some help if you're looking for something, if you're learning French (locals appreciate expats doing this effort), if you're cooking and missing some (brown) sugar.

I think that a good way to meet your neighbours or start a chat in the street or on the bus.

yep Bertrand is right and learning the language is number 1 and your neighbours will love to help you.

Go to a local women's/men's gymnastic group.

Attend the local things usually announced in your local newspaper. Go for coffee afternoon with the ladies, try to find out where they meet. If you want you can also go to bible studies, usually in the afternoons, but you dont have to. Visit local congregations. There is so much to do.

Now you have more reason to be friendly with your neighbours, its pre-xmas (advent will soon be here) bake a cake and share it with the neigbours. Buy some mandarines and nuts and put them in small bags and put them outside the doors of your neighbours with a small greeting note...

To be continued...

we've been living on the same street in a little village for the last 6 years. we know most of our neighbours...except the one living exactly opposite us, we say hello but that's about it!

until one morning he forgot to pull the handbrake of his car and while he was closing his gate, his car reversed into our car...well that evening he came over to introduce himself with his insurance details!

i don't recommend doing it like this, but it's one way to introduce yourself...