Don't Ever Use These Words
Suppose you talk to a girl for the first time after you met her or shortly after. You are trying to set up the time and place to meet, but it appears that you can't quite figure out when both of you are available at the same time to meet up.
In that situation, whatever you do, don't say: "Well, just give me a call and let me know...."
NO, NO, NO!!!
You NEVER want to be in a position of waiting for a woman's call or leaving it up to her to call you. This strategy is a loser for several reasons.
First, most girls don't call unless they are already really into you which is usually rare at the early stages of your interactions with them. They just have too much ego to call and seek you out even if they are interested.
Second, if you decide to call when you don't hear from a girl, you are going to feel stupid because... you asked her to call earlier.
So, if a woman is uncertain about when she is available, instead of saying, "Call me and let me know" tell her "OK, I will call you by the end of the week and see if you figured your schedule out a little better."
Keep the power and control to yourself. You will be much better off and you will come across as a more attractive and confident guy.