What are some safe and lively areas to live in Queens?

I am currently a grad student and I live in Jamaica because it is close to my campus. My sister will be moving up this spring/summer from Texas and we are trying to find a nice, but safe area to live in Queens. We are trying to find a place that is lively, close to the city, and close to the E or the F line. We are trying to see if we can afford a 2 bedroom apt for rent, but I am not sure what areas would be more affordable. Any help is greatly appreciated!!! :)