Seriously stop.
Calling a girl pretty, cute, beautiful, etc. is nice every now and then. It is a great compliment! I tell my girl-friends they are good looking all of the time. It puts a smile on her face, raises a girl's self-esteem, lets her know you may be interested when you first start talking to her or makes her feel loved even after years of dating/marriage. Sometimes though, you need to know when to stop.
I have a two-strike rule. If in one of our first conversations you mention my appearance more than twice, I'm done. Sounds harsh right? I must be ungrateful or conceited. Why the hell would I not like a guy calling me gorgeous in every other text? There is so much more to me than my looks.
There are so many pretty people. I spend a good deal of my time appreciating the outer beauty of others. After all, we are surrounded by ridiculously good looking people—in real life and social media. While it is nice to be good looking, that's not what makes someone stick around. Friendships aren't based on looks, they are based off of characteristics of that person's personality such as intelligence, loyalty and sense of humor. Lasting romantic relationships are the same way.
If you're spending the majority of our conversation complimenting my looks, it is only flattering up to a certain point. I, like most people, would like the guy I am crushing on to find me attractive, but "pretty" is not who I am. You'll never get the chance to find out who I am, either, if you keep fixating on my looks. Moreover, it shows me that you really don't care much about getting to know me.
I am not saying stop complimenting girls. That would be an awful idea. How else will I be able to tell if you're into me? I am just suggesting that after a guy compliments my looks, he switches his focus to what makes me different than other girls.
So, go ahead and call me pretty when you first see me on our first date. Call me beautiful when I'm all dressed up or when you first see me without make-up. Remind me I am gorgeous when I am having a bad day. Say I am stunning because in that moment, you can't help it because you genuinely mean it.
Just remember that there is more to me, more to any girl, then what you see on the outside.