Learning a new language

Thinking of 'brushing up' on my very basic French from school, any advice on the best way going forward without a tutor?

I was thinking of buying a load of school text books and going back through them from primary school level and work my way through them, has anyone used a better method?

I tried the Duolingo app a few years ago but wonder with the advancement of technology whether textbooks might be redundant in this brave new world.

Many thanks :p