For the purpose of this post, assume that Dwarves are a magical race, not humans with a medical condition which results in dwarfism (this really shouldn’t need to be said).
There are two main things to consider when creating a Dwarven race: traits that are hereditary (meaning every single Dwarf will possess the traits) and traits that are cultural (meaning Dwarves that grow up outside Dwarven lands will not possess these traits, while non-Dwarves that grow up in Dwarven lands will).
Hereditary trait considerations:
>Are Dwarfs sexually dimorphic?
>>What is the height and weight range for males?
>>What is the height and weight range for females?
>>What are the other physical differences between the sexes?
>>How long is a Dwarven pregnancy?
>>Can females grow facial hair?
>What is the general build of Dwarves?
>How well can Dwarves see in the dark?
>>How well can Dwarves see in low light?
>How difficult is it to make a Dwarf loose their balance?
>How resistant are Dwarves to alcohol and other drugs?
>How resistant are Dwarves to poison?
>How much do Dwarves eat?
>Where do Dwarves hold their weight?
>Are Dwarves’ feet short, long, or average for their height?
>Are there any other species that are in the same height range as Dwarves?
>>Do they have similar builds?
>Are there any species that have the same build as Dwarves?
>Can Dwarves mate with any other species?
Cultural trait considerations:
>Are Dwarves good at creating things out of metal?
>Are Dwarves good at creating things out of stone?
>What are popular facial hair styles?
>>Are there any Dwarves that shave their facial hair?
>Do Dwarves drink alcohol often?
>>At what age are Dwarves allowed to start drinking?
>What do Dwarves eat?
>How often do Dwarves leave their communities?
>>What professions do Dwarves that leave their communities tend to pursue?
>What weapons do Dwarves prefer to use? (Consider their habitat when answering this– if you, for example, have Dwarves living in caves, they’re unlikely to practice archery as it wouldn’t be very practical.)
Of course, you should also flesh out your Dwarven society.