My advice on a helmet "get one".

I cracked mine in April and came home from the ER to meet my kids after school. Did have a broken wrist and bruised cheek - but I came home.

I agree you need to try helmets on for a feel. Bell and Giro will fit different although they are the same company. The women's fit helmets are a smaller shell. A universal fit helmet will be under $50 with the sized helmets (S, M, L) being more expensive. Visor/no visor I feel is a personal preference.