Bill Tindall, E.Tn.
This post was to follow marking for dovetail sawing but a question below put this reply ahead.
I have gotten experienced enough that after I cut and clean up a dovetail I hand press the joint together, partially. If it starts ok I know it will be ok in the assembly.
My wife and I apply glue. We use a small flat lab spatula to wipe each face of pins and tails with a thin! layer of glue. For example, she might do the tails on one drawer side and I do pins, front and back, on one side of the drawer . Tail board is laid flat on bench and pin boards (drawer front and back) pressed into the pin sockets in the drawer side. A rubber mallet is at hand to tap the pieces together. Typically the joint comes together. I am satisfied at this point if it comes mostly together.
We repeat applying glue to the other pins and tails, place the drawer side over the pins in the drawer front and back, and tap it together. (the drawer is on its side at this point). For some reason this joint usually does not come all the way together with reasonable tapping, but no matter.
Next I take advantage of a property of Titebond. It has huge impact strength but little shear strength until fully cured.
The drawer is oriented on the bench as it would sit in use. The cauls shown are positioned over the dovetails and preadjusted clamps applied to pull the joint together side to side- two clamps on each side. For a tall drawer one of these clamps might need to be temporarily positioned in the middle of the joint to pull the middle snug. I crank up the clamp pressure to pull the joint tight as it can. Joints that will not move even with ponding with a 2 pound mallet will easily slide together from the shear force of the clamps.
The cauls are sticks of wood with poster board attached to one side. The poster board has enough give to pull dovetails together and the paper releases from the glue that squeezes out. I don't care that glue gets smeared about the drawer side as it will be planed when fitting.
Next I remove these clamps. I used a padded clamp to pull the length of the drawer tight. I only use one clamp and move it as needed to pull the drawer side lengthwise to snug the joint in this direction, as needed.
All clamps are removed and the drawer is checked for square by measuring diagonals. I find measuring diagonals more reliable than using a square because the sides or fronts/backs may not be perfectly straight. If they are not one can go crazy trying to figure out what is going on by checking with a square.
If the drawer is not square it can be squeezed by hand power across the require diagonal to coax it square.
All is well if where the drawer goes is square. On a large case it may not be. In that case the drawer can be slid into its location and wedged into position with tapered wedges to cure in what ever shape it needs to be.
In any case do not cure a drawer (or most anything else) under clamp pressure. One never knows what the shape will rebound to when the clamp pressure is released.