Objectives: Find the Sand People
Marlena will talk to you when you leave Anchorhead; her husband Tanis has done something or other that displeased her, and she'll make various vague statements regarding his death, and ask you to relay a message to him. This isn't a side-quest, as such, so forget about it for now.
Sand People will occasionally ambush you in groups of three while you're in the Dune Sea, and we can only suppose that Anakin Skywalker wiped out Tuskans that were watered down by millenia of inbreeding, because these guys are tough, especially if you come to Tatooine without a lot of levels under your belt. Their gaffi sticks can stun a member of your party on a successful hit, so bringing along Bastila might be a good idea; she's immune to being stunned due to her Force immunity feat, so she won't stop fighting. If you have any mass-stun powers, use them to break up the attackers, then single one out for destruction. Rinse, repeat.
The sandcrawler to the south of the Dune Sea has recently been attacked by the Sand People. What kind of artillery those Tuskans hide in their canes, Zatoichi-like, is unclear, but whatever it is, it must be pretty powerful to do enough damage to incapacitate a beast of a vehicle like that. Fortunately, they never use it on your party, but they'll still attack en masse once you speak to the sandcrawler's captain, in three waves of four raiders apiece. No holy warriors this time, but you'll have to be careful that you don't overstress your Force powers in the first couple of fights; you'll need to save some to cure or heal your party. Once all three waves of Sand People are vanquished, speak to the captain again to learn a bit about the Sand People's bivouac to the south. Apparently, they've set up a large number of turrets around the position, the better to destroy any approaching intruders.
Proceed still further south from here. There's an amusing diversion involving some broken-down swoop bikes, and exits to the Eastern Dune Sea and the Sand People Territory. When you see the Tuskans guarding the latter exit, engage them and kill them all; there'll be 10 or so in total, so be sure to heal up first. Grab all of the equipment that you can; once you pick up a Sand People uniform, you'll get a quest note explaining that the suits are too small for Zaalbar, so if he's in your party, you'll need to switch him out.
Sand People Territory
Objectives: Find and subdue the Tuskan Raiders
This place is populated by Sand People, obviously, and a whole bunch of mines, so stay frosty on your journey south. You might want to stick to a path near the markers on your way down; the game has a nasty habit of assuming that you're lost and warping you around if you get near the center of the map, which can separate your group.
Once you spot the enclave, dress everyone up in Sand People uniforms and proceed inside. You can try a frontal assault, if you like, but the turrets that are set up in front of the entrance are incredibly resistant to most forms of damage; good luck getting past them. Make sure HK-47 is in your party, if you intend to pursue the best Light side course of action; luckily, the party-switching feature of your map screen is still enabled in this map area. Of course, if you're just gonna cause a ruckus, you can bring whomever you want to the party.