Find a picture of something similar in a room. Honestly, Houzz is the best place. Designers and architects takes the guess work out of what goes with what. It's like paint by numbers. If you're looking for a blue and white chair type just that into the search and then bookmark the link, add it to your favourites etc. When you're not standing in a store physically the fastest and simplest thing to do is say I'll send you a picture of exactly what I mean to anyone who is helping you. As the saying goes a picture is worth a thousand words, and will greatly expedite the time you would otherwise waste trying to describe what you want.
Get help. Figuring out what you want exactly is half the battle. And by help I don't mean a conversation with a customer service agent sitting in a call center, who hasn't a clue what to tell you beyond the same twenty five words you just read in the description! Honing in or narrowing the choices is extremely helpful when you have a product expert at your disposal and many online sites realize the important of this and are adding them to the mix. They likely come with years logged in sales showrooms or buying roles and will be able to tell you in a split second the difference between this thread count and that one, for example. We call these product experts Stylists at remotestylist.com and they are always free and on standby waiting to jump into your next project.
Ask for samples. See, touch and feel. Just because you're shopping online doesn't mean you can't do do this. Sitting, sure, is a little more difficult but those who make the product realize you need sales aids and are increasingly becoming more willing to send them to you. Fabric swatches, stains, drawings for custom pieces, etc. If there is anything you are hesitant about, or questioning, regarding a product ask ask and keep on asking.
Test the waters. Buying without trying .... who isn't afraid of this? But do you really have time to sit, touch and feel every item - probably not. Building relationships with online sites and the team behind them only gives you more confidence in your own purchasing decisions. As you get to know them, and they you, you can both start filtering out what you don't want and get to what you do a heck of a lot faster. That being said you have to start somewhere so test the waters with less expensive items, generally accessories, lights, maybe a mirror to familiarize yourself with the overall process. Sure you may want to do your whole room, and yesterday, but the two weeks it might take to get your first purchase delivered goes miles to building confidence and trust in building a good relationship. With shipping features like $1 everyday, duties included, you really don't have anything to loose by splitting your order!