My friend has a her first crush!!!!!!!!!!!!!!?

Ok my friend has her first ever full time crush, she is 12 and the guy she like is 13, it is her friends brother and she doesnt no what to do! should she go round to her friends house more often to see him or should she ignore him! she doesnt no if he likes her or not, should she flirt or not? PLZ U GYS ARE REALLY GOOD ABOUT THIS STUFF PLZ HLP QUICK!