After a few odd purchases, I've taken some notes to prevent poor sizing, bad quality etc.
1) Shipping is always slow with zulilly. I almost forgot that I bought an item at times.
2) The no returns policy is complete BS.
3) I don't like the fact that items have no reviews from other customers.
4) I now pay very close attention to the sizing charts, clothing material, and the pictures.
4a) sizing charts. If not explicit or vague, I look up the product on another website. If still vague, I may not take a chance.
4b) Material. Sizing is flexible if the clothing has some stretch or is made with good material. Polyester is polyester. Wool is wool. Acrylic is cheap looking after one wash. You get what you pay for. Pay attention to what you're putting on your body. Or your floor for that matter. I've bought some beautiful wool rugs for a good price on Zulily.
4c) pictures. Is the shirt wafer thin? You can tell online many times. If there isn't more than one view, unless I'm familiar with the product, I won't buy it.
5) Zulily is great for discounted staple brands sometimes. I bought deeply discounted camping supplies, lights, thermoses, etc. that were quite handy. I know the designer purse stuff sells out quick, but its not my gig. I use dansko and sanita shoes, OTBT, and good leather brands, and sometimes I see a great deal on there. I always check a competitors website if it seems on the edge of a good deal. At times I've found better deals on Amazon, at times, on Zulily.
In sum, don't just look at a pretty pic and click buy. Think about what you're buying, if you know the brand, and if there's a better deal to be had somewhere else. If you need in a hurry or need feedback, Zulily is not your website.