How do you react when someone gives you a present?

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I don't know how it's with you people, but I'm very bad at receiving gifts(and giving actually). I do like to get one (or more lol), it's not that the present is stupid or something. It's just that I don't know what to say or how to react. Situation: nice friend/familymember gives nice present, you do are happy. Then I start to think: I'm really happy with it, so I have to say or do some more than 'thank you', but what? It's not that I can go totally mad with joy, that's over the top and will seem fake...mmm what to do...And in the mean time, your friend/family member is waiting anxiously for your reaction, almost immediatly after you opened it, they start saying 'well if you don't like the colour you can change it', or 'I hope you don't have got this book already', or 'it's just a little something, nothing special'. And it ends with an awkward silence for 2 minutes or something (while I'm thinking what to say), and me just saying thank you and start blushing. So how do you do it, receive presents in a grateful and enthusiatic, yet true way?