My acquisition of French has been through immersion, since moving to Île-de-France Region in 2010. Not shy, and needing to communicate, my first discovery was that simply speaking English with as strong a French accent as I could muster went a long way to being understood.

Adverbes multiplicatif

bis ter quater quinquies sexies septies octies - are used to add in extra house numbers in a street.

Grammar is stricter in French

- I quickly discovered to my dismay, but it does allow extraordinary precision, as pointed out at leslivresoublies (they also do an Android app if your device has a high enough screen resolution).

French articles and determiners

Bertrand Boutin offers an excellent page on "l'article" .