Step 2: Put the Lime in the Coconut...
Measure out one quantity of hydrochloric acid and pour it in. ("Do like you oughta, add acid to water" to minimize the chance of an out-of-control exothermic reaction.)
Be careful with the acid. This stuff (at 10 molar) is strong. Mine fumed a bit when I took the cap off. Don't breathe it directly, and be sure you've opened the kitchen window.
The starter etchant you've just made, on the other hand, is not so bad -- around 3M HCl with a medium-strong oxidizer. I find it doesn't fume much at room temperature when I'm re-using a batch.
That said, you've got to be very careful to keep it away from metal -- especially your stainless-steel kitchen sink. It'll eat the stainless coating right off. Keep plenty of water flowing at all times when you've got any of this (even a drop) near the sink.