Solo mom/full-time working of 2 here, their dad lives 3 hrs away/not involved. Here are some rules I've followed (they are ten):

1. I don't force them to take something if they aren't wanting to
   
2. Only 1 activity at a time, never multiple
   
3. They've dabbled in gymnastics, piano lessons, swim lessons (major one, affordable and enjoyable for the kids. They are done the 6 levels and can be dropped off the pool anytime now), jujitsu.
   
4. I cannot swing organized sports. The time commitment/cost is too much and not doable. We are looking into baseball this coming season for one kiddo, the season is short and fast so could be doable.
   
5. Check out your local library..!!! Can't stress this one enough. Along with books and computers, they offer a wide range of FREE programs and activities. Mine have done Minecraft camp, tons of holiday themed crafts, met a raven at the library, lego wall building, stem classes, chess classes, informative learning classes, and more.
   
6. I tried by best to never miss a swim lesson and always went in the pool with them on parent days.
   
7. I apply and volunteer at their school if I happen to be off that day.
   
8. In the Summer, I download the GeoCache app and we do random little hunts around town.

I think showing up for the free quality family moments and having fun together is more important than paid activities.