This is the latest update on the varnish-fix saga, but before that I'll try and answer the points raised.
It is correct that there is a tissue-type paper between the decal letter etc. and the paper outer. The outer paper is somehow "lightly glued" to the tissue paper. The tissue paper has a brand name which I can't remember but apparently it is no longer manufactured; hence no more varnish-fix transfers [there are now more easily attached decal methods].
The tissue paper is attched to the decal letter etc. by a water-based gum. When you reach this stage, the tissue paper can be removed by completely soaking in water. Some folks advocate warm water but this is not critical. I add about one drop of washing-up liquid to approx. half a litre of water. This helps to break surface tension and allow the tissue paper to slide off the decal, which is preferable to lifting it off.
Back now to the outer paper. There is no need or advantage to remove this from the tissue paper before placing the decal in position on the frame. In fact the disadvantage is that the locating marks on the outer paper are discarded - and this is hopeless !
To go back, I put a band of masking tape around the frame top and bottom of where decal will be placed. I mark the centre of the frame by keeping my face close to the frame and with a ruler note that you can see "approx. 30mm width", visually lining the ruler up against the down / seat tube; obviously 15mm is marked off on the tape, being the centre. You draw in the centre line of the decal if it is a dual, if it is single, attach a small tab of drafting tape at the top and bottom of the decal and mark the centre line on these.
There are a few general tips. For bands which encircle a tube make certain that they are not going to overlap at the ends.
Now to laying the decal, when the varnish is tacky [I use Johnsons Yacht Varnish, it is thin and clear and dries to tacky in approx. 30 minutes minimum]. I pull the tissue layer away from the outer paper on all four corners and slightly chamfer each corner of the tissue paper before varnishing. This stops the tissue paper curling when varnished.
Line up the decal on the frame and press down along the centre line to make certain it is in position.
Now this is important; have a fully squeezed-out sponge [car wash type] so that it is just damp and put this on the decal and press the remainder of the decal around the tube. Discard the sponge now. The barely damp outer paper will still be attached to the tissue paper and to easily remove it, start at one top corner and gently roll it back along the long side to approx. mid-point, pressing the tissue paper whilst doing this. Repeat from the bottom corner to mid-point and then roll the whole length of the paper across the width of the decal, pressing down the exposed tissue paper until it is completely removed. Press down all over the decal; I use a finger nail and also a paper handkerchief.
Leave this now until it has dried completely, then apply water [as above] to release the tissue paper.
Finally, I will just add that apparently those that know, use a glue stick or thinned PVA glue instead of varnish, but not for me. I've learned the hard way !