1. period + start a new sentence
   
2. comma + a cute little conjunction (and, but, for, nor, yet, or, so)
   
3. semicolon by itself. Where you have used a semicolon, you could have used a period, but the semicolon, you felt, is better (probably because the independent clauses are so closely related and nicely balanced). In spite of her cold, my mother refuses to go to bed early; she is afraid she will miss something.
   
4. semicolon + big ugly conjunction + comma (however, moreover, nevertheless, therefore, as a result, consequently . . . ) My mother has stayed up late four nights in a row; as a result, she cannot seem to get well.