If you are a hobbyist who has purchased rare succulents chances are you have had a plant arrive to you as either a cutting or that has little to no root structure. This is a rather simple fix, there are many methods to get that stem cranking out the roots. I follow the advice a very educated Korean grower shared with me, which is to just sit the plant down in semi-moistened soil and allow the soil to dry out for a day or so before you moisten it again. Pretty soon your newest succulent friend will be thirsty and it will send out roots in search of water. I withhold any real amount of water until I start to see a healthy root structure form. Just a simple misting of the soil every couple of days will be enough to keep the soil humid and the plant will take it from there. If it is an echeveria or agavoides type of plant I just sit it in a little saucer of soil about an inch thick. It is very easy to overmist -- just remember soggy soil + no roots = a soon to be rotting plant. Just keep your soil moist/humid and wait for the roots. Your plant has more than enough water stored in those plump, chubby leaves to take care of itself in periods of drought.