This is a tough one for me as far as clothing goes..because of sizing...but here is what I am LEARNING to do. Know your dimensions and then look carefully at the sizing chart for the specific store you are ordering from. It can really vary. Actually what I do is keep on hand the sizing charts for the outlets I buy at and then can be a bit more confident when ordering online. It’s not foolproof but a bit safer.
I have used: Appleseed’s, Lands’ End, Coldwater Creek, Travelsmith. These are NOT EXACTLY budget retailers but when they have sales they BECOME reliable and value-conscious choices. With Lands’ End and Coldwater Creek you can return your online purchases at their stores which is convenient.
I sometimes use Amazon.com for beauty products but not before checking them out at a bricks-and-mortar store FIRST.
Also have bought shoes online but again usually only after I have tried them on at a shoe store.
And finally, yes, FREE SHIPPING is important these days.