#1 Everyone else says yes...
... but you. If you're feeling the pressure to get the gown just because everyone else thinks so, well, don't. If it doesn't feel right or if it doesn't feel comfortable, then put it back on the rack. if you're really undecided, then take a day or two to mull over it before sealing the deal. And as we always say, it's best not to bring an entourage when dress shopping - too many opinions can ruin the shopping experience! (See: 4 reasons why you should go wedding dress shopping alone)
#2 It's the wrong size
Yes, we know the temptation of getting a gown that's on a crazy discount. But if it's two sizes too large, think twice about getting it. Major alterations can alter the cut, shape and original design of the gown, and it might hang funny on you too. Ditto when it comes to getting a smaller gown thinking you can lose weight in time for the big day - consider a dress with a corset back so you can easily make it tighter or looser.
#3 Talking about bargains...
It's all good if you've found the dress of your dreams, and at a cheaper price too! But just be sure you're really in love with the gown, and that it fits you right - it shouldn't just about you getting caught up in the thrill of a great buy. Also, be sure to check the dress for flaws, stains and tears since it's probably been tried on by many brides-to-be before you.
#4 It's not venue-appropriate
You've fallen in love with a gown at the boutique - a grand duchesse satin ballgown with a mile-long train. Except... your wedding's at the beach, or on a lawn. If you're about aesthetics over practicality, our hot humid weather might make you regret your decision on the actual day.