a good method that always works for me, both in cases of a bit of overly-dry tar, and not so dry tar, is to take a couple of drops from my eyedrops, and drop that in the foil boat. Rock back and forth, dope dissolves easily and very evenly.
As to using plastic intake tubes, I don't like 'em. I tend to get a lil' close to the surface of the foil, and the plastic will usually start to melt about halfway through the first hit.
tastes like vinegary dmt, but not anything of the sort. eech.
what I do anymore is to take a length of foil, roll it smoothly around a pen tub, and crinkle the ends a bit to make it hold shape. This tube collects resin, and after smoking one gram of tar through it, you should be left with a good, solid nod left in residue.