Grey can look very professional for work. You need to pick the right grey for you. A very dark grey could be perfect or it could overpower you. A pale grey could work wonders or could wash you out. As with all colours you need to see them against your skin tone and preferably in a natural light.
A friend with an honest opinion helps and you can compare different grey’s against your skin tone.
A sales assistant who tells you the truth is worth her weight in gold – ask her opinion, get her suggestions and show your appreciation. All sales assistants should be honest (but this isn’t always the case), if you get home and you hate it then you’ll just take it back, a waste of everyone’s time.