I usually look for electronic gadgets when shopping online because they are usually cheaper compared to buying here in the stores.
Pricing, Return Policy, Refund Policy & Terms and condition of the site if site is new. otherwise mostly pricing matters.
I absolutely love shopping online, however, I refuse to buy anything from anyone that ships with DHL.
I always try to find the best bargain.. The cheapest shipping and the coolest, most unique items.. Then I check out the return policy and if I've never heard of the company or user I might do a bit of investigating before placing my order..
If I have in mind what I want to buy then I'll do an extensive search on it online until I can narrow it down to at least 3 stores. Next comes store reputation and if it's a safe and reliable place to shop. A good amount of time is spent researching the site's feedback on random Google searches or Yahoo! Answers (really helpful actually). I use PayPal for all of my online shopping so I don't really worry so much about privacy. If the site doesn't accept PayPal then I won't bother. Then again, when it comes to eBay it's a whole different ball game. Easier really. All I'd have to look is at the feedback and shipping charges.
I look for stores that sell familiar brands that I'm use to or either very unique ones where I can't find these types of things (clothing mainly) offline.
prices, discounts on bulk orders and the damn shipping I buy shirts almost daily from different websites, I have some 200+ tshirts in my closet, some shops like FCUK don't have all the shirts in stores that are online, and shipping is the killer, site like woot shirts is very nice, I vote for a design I like and if it wins $10+ free shipping, or $5 for overnight.