Well first off congrats on wanting to do the right thing as these days from allot I see parents just don't care.
Give them plenty of love and spend as much time as you possibly can with them.
As for activities scouts could be a good start as they are shown many things there are always things they will like and choose to do on their own. What ever activites you and your wife grew up doing pass them along and hopefully the girls will to find one or others they enjoy.
We started camping with ours from day one and turns out both girls now 12 and 14 absoluetely love to camp they also fish and are getting into shooting.
Just do the things you know and start from there. I wish I had introduced one of mine to sports at a young age as she would have been good.
One thing to remember is you will make mistakes we all do don't dwell on them learn and move on.
Best of luck.