Many mistakenly believe that braided line will slip on the spool unless you take Draconian measures to prevent it. Experience has clearly shown that putting on several layers of mono, Dacron or duct tape are totally unnecessary. This practice is not recommended to solve a problem that does not even exist. Braided line grips the spool much like tread on a tire grips the road better than a smooth one with an infinitely small contact area.
Before you start spooling, form a good knot, (such as the Berkley Trilene knot) cinch it tightly on one side of the spool leaving a long tag end to be laid across the arbor. Spool the first full layer of braided line onto the spool in a close side-by-side fashion under tension of 6 or more pounds over the tag end. If this is done, the line will not slip! No exceptions have been reported but try pulling on it at this point if you have any doubts. When convinced, you might tell a friend that it works.
Continue filling the spool under tension without any exaggerated crisscrossing. Tension about 1/2 the drag pressure expected may be appropriate when spooling heavy- duty line. Exaggerated crisscrossing creates open space in the spool which may invite the subsequent layer to dig in. In any case, crisscrossing is a one-time-event because you would not attempt exaggerated crisscrossing when fighting a fish because to do so would give the fish the opportunity to shake the hook. Actually, even if you think you are laying the line tightly under tension in a close side-by-side fashion, it is likely that you can’t see that you are crossing several wraps every turn because the line is so small diameter.
Some believe that braided line should be spooled on wet. This is not needed, but if it makes you happy, ok. The main concern with wet spooling is that often insufficient tension is applied. Fresh water causes no problems, but I would not use sea water which has about 3.5% salt (about a 1/3 pound per gallon). Salt causes spool erosion. You would be saturating the line with salt all the way down to the bottom of the spool to start trouble later.