1.The most important thing is getting one that you are comfortable wearing.2.Next you have a choice of a wide or narrow view,myself I prefer the wide view.3.Next the lighter the better,but the lighter the higher priced.
4. If you pick the size opening wide or narrow that you like best and a helmet that fits comfortable,not all helmets fit well on everyone or at least not for me.As long as you buy one with that meets NHRA & IHRA requirement for your class/speed you will be fine!
PS I have been Racing dragsters since the mid 90's.