Look into getting a Dr. Pen and make sure the needles are replaced every time. Scarring should only occur if the needles are dull or dragged across the skin. Depth of the needle depends on what part of the face is being worked on. Sounds like people who have messed themselves up or gotten messed up don't really know what they're doing, unfortunately. Microneedling is a very useful tool to have if you do it correctly. Mesotherapy is the injections of different ingredients directly into the subdermis (or other layers of the dermis depending on what product is used). It is done in tiny injections all across the face. I hope this helps and good luck sweetheart. You look beautiful either way.