Simple as that. I don't mean like repetitive and harassing texts, but what is the limit to how much you can text a girl?
Most Helpful Guy
If you are an interesting guy that can engage people in a conversation, or even if you are shy but genuine, it's always good practice to speak to the girl you're interested in just briefly through texts. After the brief texting (to judge if they are busy) either call her or meet up in person.
I try to keep texting a girl I'm interested in to roughly 6-7 texts at a session. Maybe 2 sessions a day. That means that periodically through the day, I will chat back and forth, like instant messaging almost, responding and teasing her. After those sessions, I'll call her if I want to or I'll meet up with her in person if I have the time.
I strongly advise you to NOT kill your attraction by texting her boring things; keep texting solely for fun and light-hearted chitchat or for judging if someone is busy; don't use it as a method to get to know someone. The same concept applies to chatting/IM'ing/messaging/commenting/etc... You should spend the effort to get to know them either face-to-face or over the phone.
Keep in mind that some girls dread talking on the phone; keep the conversation fun and light hearted. Practice your social skills often and brush up frequently by going out on the town with your friends. The more you practice with others, the better conversationalist you will appear towards the girl of your interest.
You don't want to be the friend; you want to be the boyfriend.