Consider your budget, type of grinder and the design of the top dome. Hand grinders are generally cheaper than electric ones. Although burr grinders are more expensive than blade grinders, they produce better quality coffee. Furthermore, large curved domes are more comfortable to use than flat ones.
When shopping for a burr grinder, beware of false ones. An original burr coffee grinder should have sharp opposing cutting surfaces. If on a tight budget but still want a burr grinder, go for a conical burr grinder that is slightly cheaper. An original burr coffee grinder should either be ceramic or stainless steel and should have efficient power from the accompanying motor.