These are people whose homes are natually desert or dust worlds or prefer to live in caves.

Tusken Raiders
Also known as Sand People, these tatooine natives wander the wilds of the Jundland Wastes. They live in family groups, only the males hunt. But the males are warriors, they will not hesitate to kill or torture any unfortunate being who crosses their path. They don't like technology but they will use it.
They are bipedal, but otherwise their true form is not known, as they always wrap up in cloaks, rags, a dust mask and goggles. They have been known to kidnap humans and raise them (or force them) to join the tribe. However, they cannot interbreed.

Jawas
These small creatures have glowing eyes and conceal themselves in cloaks. They too, live on Tatooine. They live in family groups and travel in Sandcrawlers, long ago abandoned by mining companies.
The Jawas are not well known to observe the niceties of ownership. If it isn't locked down they will take it. However, they are elusive rather than warriors and usually cowards. They also have astonishing skills at keeping old machinery working (at least long enough to sell it.)
Geonosians
Insectoids from the harsh, dusty Geonosis. They have exoskeletons and have two classes: wingless drones and winged 'aristorcrats'. They are a hive species rarely seen outside their homeworld. They have a strict cast system, including queen, warrior,,worker and probably others.
The Geonosians had extensive droid factories, which were used for the Confederacy during the Clone Wars.
Arconans
Reptiles with no scales, they come from Cona, a desert world and prefer living in caves. They don't see well, but are excellent fighters when defending the hive from predators. In appearance, they range from grey green, to browns, to nearly black in coloration and have claws. They also have a strong sense of smell.
Arconans need a substance known as 'dactyl' to survive, and this substance is depleted if they ingest salt, making salt a deadly substance. Nonetheless, they addict easily to salt. A salt addict can easily be spotted as their green eyes turn gold. They live in family groups and do not have a highly developed sense of 'self' or 'individuality'.
Arconans have created enclaves for themselves on various worlds.
image from Wookipedia.
Talz
They come from Alzoc III, although they also had a colony on Orto Plutonia, though how they got their at the pre hyperspace stage of development is unknown. It is unusual to see one off their homeworld.
White, furry and large with four eyes (day and night vision). They had a small proboscis to commnicate and eat, and have large talons. They tend to be gentle and hard workers.
They lived in complicated family clans, but their size and the convenience of such a large sentient right near mineable minerals led the Empire to enslave them. They were freed by the New Republic, which now trades for the minerals.
image from Wookipedia.
Nelvaan
Blue furred and naturally wiry, the males were experimented on during the Clone Wars by the Confederacy, leading to genetic mutations.
Their traditions equated the planet and nearby river with 'mother' which kept the planet warm enough to be livable. They tended to paint themselves when preparing for battle and tested the young warrior males by hunting giant creatures in the wild.
image from Wookipedia.
Twileks
A species that comes from Ryloth, a world of harsh extremes, dangerously hot on one side, dangerously cold on the other and subject to fierce storms. Their people have been known as both warriors and dancers.
They come in many colors, but all have prehensile twin head tails and tend to eat molds, fungus and some meats. They live in clans which don't always get along and have a high council.
Due to their exotic beauty, the twileks were the victims of much slavery. Women were often sold as dancers. As a species, they ranged all the way from criminals to noble warriors to jedi knights and Alliance pilots. During the Clone Wars, they were divided when some individuals sided with the Separatists and 'officially' they were still with the Republic. This led to their invasion.
image from cantina00 Photobucket.
Sullustan
This species comes from Sullust, where they live in caves. They have large eyes which see weell even in the dark and large ears with great hearing. The eyesight does tend to deteriorate after a certain number of years and they often need treatment. They have dewlaps. They rarely have any hair.
They live in warren family units and are, as a species, open and friendly, strong believers in capitalism. They ended up with the Confederacy in The Clone Wars and then served the Galactic Empire when the SoroSuub corporation took over the government. Although, made up of Sullustans, their were enough who disagreed with the Imperial support to lead a resistance movement. While not officially a member of the Alliance, they did ally with them in certain battles.
Image from Incom T65 Photobucket

Kel Dorian
The species comes from Dorin, a world with much dust but no oxygen. In fact, they have to where masks to protect themselves against it when off world. They had a tusk like face and odd extra sensory organs that look like tusks. It is not uncommon for them to be force sensitive.
They tend to have a very black and white moral code. Their most notable group were the Baran Do sages. These force sensitives largely escaped the purges. They tended to guide their people through disasters.