Right - get the lather going with a damp brush - it won't do much except increase a little in volume, but it'll still look like smeared cream/soap. Dip your cupped fingers (not the whole hand) into your basin of water and add a few drips of water to the lather bowl. Work it, check, then repeat. Once the lather starts building but still sounds sticky and tacky as you work it with the brush, add a few drips more and then whip it. Hard. Think of making meringue. OK, don't go so mad that you wreck your brush, but don't tickle it either. You should hear the sound reducing in volume and getting "wetter" and less tacky-sounding, if that makes sense, and the lather should really be building now. If it doesn't, add 3-4 more drips of water and continue whipping. What you want is a smooth, glossy or pearlescent lather with few or no visible bubbles which, when you pull the brush from the lather bowl, generates a decent peak which wobbles around when you gently shake the brush but which doesn't collapse or fall over. If it does, you've overdone the water; if the peak is short, stubby and stiff you need a few drips more water and more whipping.