Guitar Fundamentals is a great place to start!

I also recommend just doing the "Classic 1-2-3-4" finger exercises. It doesn't have much of a direct musical application (except for chromatic scales) but it's great for warming up and getting the agility happening again, and it was actually one of the first things I ever learned.

One finger per fret, start on low E and play frets 1, 2, 3, 4 in order, one with each finger.

Pick: down, up, down, up.

Then move to next string, repeat.

Go up and down the strings several times.

There are many variations on this that are a lot of fun! You can go 4-3-2-1, or 1-3-2-4, or change it in any way you'd like.

Go slow and keep those hands in sync.

-Carl.