You read it, decide if the criticisms are valid. If they are, you try to consider them next time. If they are not, you ignore them.
I can't stress strongly enough that you have to detach emotionally from things like this if you want to do this as a career. I see people say they don't read reviews, but a lot of negative (or middling) reviews have good points about how you can improve your work. Good reviews are far less valuable (though more fun).
If you let reviews depress you, you're going to have a hard time. A quick little wave of unhappiness is one thing, but then let it go.
I have a one star review that gushes about the book (an obvious mistake on the star rating), another one star that lists an old book and basically says, "I didn't read this book, but I can't imagine how anyone can write on the topic better that XXX," and still another that is a ten paragraph rant about how she couldn't download the thing. You can't let this stuff get to you.