First of all Check your own Body Measurements take them and write them down and place them in easy reach of computer! Also look at the chothing you like to wear in your closet so you have idea of how long the skirts,pants tops etc fit  on you !
                    2nd keep an open mind and ask the measurements from the seller or if you like to see the back most sellers will send you pictures or measurements though some may need a little bit of help from you ! Explain how to measure the item! On skirts I do waist and length in inches as well as size on tag, after all even new items dont always have same size as we think they do!We find they don't fit when we put it on! Items that have been washed may be smaller as well and sometimes tags are missing!
                3rd  ask Questions I notice that when iI Photo graph certain colors they look faded or reflect a bit different then they are in real life and photo shop helps some but not perfect! So dont be afraid to Ask  But Please if its 5 minutes till it closes dont think can get back to you if it has no bid write me and i get back to you and will relist it if your interested!I check My items 2 times aday except when not home!
         Plus Sizes or BBW sizes are the worse about not being the same a 3x for one Brand will be a 1 x  for another or 5x for yet a third !So buyer beware Ask Questions ! The Seller wants you happy so they should be careful to answer your questions! I for one hate to have returns or bad feed back because the buyer isnt happy sometimes that happens but I try to give as much information out as i can! I write whats on the Label : Brand Name, what it's made of ,size and any other information I can glean from the Label! Like hand wash or dry clean only! Then I measure it in inches waist Lenght Hips instep and bust etc! It helps the Buyer get a better picture of what I am selling! Since he or she can not touch the item or try it on!
      Children"s chothing remember to buy a bigger size then your child is in Now! Especially during the fast growing times of childhood! Teens, well they need to be shown the item or else they will not be happy,. if they did not have had any choice or say in the matter and again Measure them all for a proper fit!
                       I hope helps you make better decisions to buy chothing on Ebay Thanks for your time Big Ed