The leaves are best inserted at an angle, into your growing medium, allowing some of the leaf to be out of contact with it. Insert at a 45 degree angle, into the rooting medium -see below. You can cut the leaf, cleanly, allowing just the stem to be in contact with the soil.

You don't need other leaves, to ensure propagation, from my experience, and I use vermiculite or perlite, to root them in, rather than standard soil - you can always make a mix, if you wish, but keep the vermiculite content higher: it allows more air, which helps keep the leaf in good condition.

Don't have the leaf in direct sunlight, as this is likely to damage it! Good bright conditions are ok, and will allow it to photosynthesize.

Keep humidity constant, and allow the plant to be warmed from the bottom, if possible;though summer warmth should be

ok, just don't let it get cold. I cover mine with small plastic bags, but beware of too much damp, which can cause rot.

After 5 or 6 weeks, you should find that the leaf's stem will have rooted and a few little babies will have formed: separate these, perhaps into the same pot, with fresh soil. I allow around 3 plantlets per pot.

Always water your plant from below too.