Make sure your microgreens have enough light!
Usually placing your microgreens by a sunny windowsill should give them enough light to grow but if you are noticing that they are getting long and spindly then it is a sign that they need more light. Besides placing them out where they can get more sunlight the video below shows a way you can set up a little grow light for your microgreens anywhere.
Also, if you are growing your microgreens by a window you will notice them bend towards the light. It's nice to rotate them around every day or so so that they are not only growing in one direction their whole lives.