I like to use one of those semi-plastic cards I get in the mail that are about 1/16 thick.
Some times drill a hole to match a dowel diameter or in the case of a tenon end just slide the card close to one side.
Usually the longest side.

Then use a ryoba saw to cut flush the thickness of the card.
Then a low angle plane or block plane or wider chisel ( very sharp ).

Works great, fewer sawing mistakes.

Enjoy the shavings!