Hear hear! All this moaning about sales going down, but no effort going into making shopping online (or even in shops) predictable and dependable.
Your size guide has body measurements. Use those (not other, made up numbers), when you design your patterns.
Your finished garment has measurements and a certain amount of ease. Post those. Front rise of trousers, waist width, hip width and at what point under the waist that is, length of sleeves, length of skirt/dress (there is a special place in hell for those who just put "knee length" or similar), bust size.
Learn all those "archaic" terms for the details of clothes and descripe the clothes with them. Raglan sleeves or just dropped sleeves? Peter Pan collar or button down? Flared skirt with gores (how many?) or a-line? Trousers are ankle length, palazzo or just wide, capri?
Don't make me search for material composition you sneaky feckers.
Model clothes on a thin model and on a fatter model, please. Helps me make my mind up. Say what size and how tall the model is. Helps us imagine garment on us, thank you. Don't lie.
Add pockets that work.
Use better quality fabric and more natural fabric.
Don't make everything in only black, beige or either pink or icy blue (this is a Sweden specific problem).
Perhaps look into sizes that vary depending on bust fullness. Can't be that bloody hard, several companies have done it by now.