Yeah, that's all you need to do. Take a dollop of mud and stick it on your palm (apparently the palm works better than the inner wrist; I just googled and came up with
this), leave it for a minute, then wash it off. If you have a bright orange stain on your hand, your henna is ready.
ETA: I know you said you have cheap cameras, but if you could get a picture in good lighting (either outside or next to a south-facing window) that would help a lot. I find that when I take pictures with my phone (which doesn't have a great camera) the colour isn't very accurate if it's indoors, especially in lamplight, but if I take pictures outside they give a good indication of the colour of my hair.
Bookmarks