To pick the right color I recommend not to buy any kind of extensions on the Internet. You can never compare your own hair color with a picture on your computer screen. Your own hair color may contain a warm glow while the extensions are based on natural hair colors without any warm glow. Also your hair can contain not just only one color, maybe even two or more. The sensible way to buy extensions is to visit a professional hair shop.
You can buy instant extensions. You don't have to fix the clips on the hair anymore. I bought individual hair strips and clips. You should buy the clips in the same color as your own hair. In this way you'll create an extra natural effect and avoid embarrasing situations (see my experience).
The more expensive the better the quality, that's the rule and it's definitely true. If you decide to buy cheap hair it often contains synthetic hair, fake hair. Synthetic hair gleam a lot and feels soft. However, after brushing and after you take a shower, you know it's wrong shit hair which do not even look like hair anymore. You can recognize real human hair by the (split) ends.
I also recommend to buy remy sorted hair. This means the hairs are sorted based on the hair scales. This ensures that the extensions last much longer.
The best way to be sure the extensions will not be noticed, is to cut your hair in layers. And you may even have to cut your extensions too. Otherwise you'll see your own hair length trough the extensions and thick hair even more. And believe me, it's not sexy. It's take some effort to let your extensions look beautiful on you, but in the end you'll look hot hot hot. Don't forget, thick hair would need more extensions than thin hair. Otherwise you will still see your own hair.
I bought clip-in extensions two times already. First ones I bought at the hair shop. This wasn´t such a success.. the woman gave me the wrong color and after the hair dresser had made them lighter, they became all dry. Adios 180 euros. Second ones I bought on a market. They are beautiful, but I can´t deal with the fact that there are clips on your head the whole day long. I can´t just whip my hair and you have to check frequently if the clips are still on the right place. It sounds strange but once one side of the extensions were on my head and the other side was somewhere on my shoulder. Yeah.. big fail.
Now you know how to recognize real human remy sorted hair, you also want to keep your expensive hair healthy. You really should buy quality products. Maybe you think the extensions itself are already expensive enough, and you're right. But extensions do need a lot of care. And yeah, if you still think it's too much money, the cheapest way is to grown your own hair and keep it healthy.