Firstly read the all review because that reviws gives a look and feel.if certain cloth have god review then that is good buy.but some have bad review then skip it.
Chech the your size matching chart.then find your size in chart .some site give the size in model wearing.so we dont hsve clear idwa about it.
If your regular shopprr on site then list the data you need continue like height , size etc .The most important is the review of return policies .Ensure that the return policies and refund without any problem.