Hey Bernie,

Keeping those wedges small...real small (width), and mocking up your joint,
really helps.

By doing the mock up, you can calculate the inside angles of your mortises,
to match the spread you get (should only be a couple of degrees) when
inserting your wedges into the tenon.

I think the best tip would be not to use them, unless gluing the joint, for
some reason compromises your project.

Cheers,

aw