A couple of things:
Cold approach.... even if you are good at it, is at best a 10-20% success rate, meaning she'll meet you on a date. If you aren't good at it, then you might get a 1 out of 20. It takes A LOT of skill, and most of that is correctly IDing women that are open to your approach.
Women will give you their number without ANY intention of her ever responding because she is just trying to get rid of you. She will just screen out your call. The reason they do this is it's too much trouble arguing with a man that has just approached her. If you call and she doesn't answer, don't get butt hurt, just delete the number.
On texting: I used to say never... but it seams to work out better if you are trying to set up dates now a days then calling. BUT, playing digital footie with women is a waste of time. The only 'text' you should send a women is asking her out. I would prefer calling her since you don't have to wait for an answer. But I will say that on the few times I've asked women out by text, they flake MUCH less.... I don't know why, but I suspect that when you call a woman, her knee jerk reaction is to say yes.... even if she doesn't mean it, only later to hear "Something has come up." I don't think any date I've set up via text was cancelled.