I've propagated mophead and lacecap hydrangeas, and from what I've read oakleaf hydrangeas are done the same way, although the success rate is lower. Astilbe I've divided to increase my plants, but never tried growing from cuttings.

Astilbe is most often propagated by seed, or division in early Spring.

Oak Leaf can be done now. Remove all the large mature leaves. Should root fairly easily.

Astilbe, seperate now or in spring. If they get plenty of water they will expand fairly quickly and you can usually tripple the number of plants each season.