There will always be an initial friction will be there to go out and buy stuff for you. You can say you are going to buy stuff for your sister and who is of your size. This rule we most of us use it for shopping but all you need is little courage. Better to go to big shopping malls and there no one cares about your reason for shopping. Sometimes if you are not been able to decide on the color you want to buy your dress you can take the help of sales girls by asking them for your sister of your complexion.
Some of us dare with the sales girls that it is for us only and they will feel little comfortable and will show you the better designs and patterns. But the catch is you can always say it is for a special occasion like some jatara or for some ritual.