Personally I deploy a loot system where I give the players what I want them to have. The players are pretty high on the XP count so sometimes I don't award XP's and i'll award loot instead. For example my Jedi player was after a Krayt Dragon pearl, I told him that if he wanted one he would have to role play getting it. My first idea was for him to tackle a Krayt Dragon but that would have been too difficult to work into the main story arc so instead I had him loot the lightsaber of a Sith he killed. The player had to make a mechanics check to salvage the part and then had to spend several days attuning the crystal to his own resonance.

The GM calls the shots and no player should be allowed to derail the game, anyone who has a problem with the GM's rules is welcome to leave.

I would utilize the encumbrance rules, and also inject Irony.

As the player's PC comes up to the body of the dead NPC to be looted, say loudly " you look over the body. that rifle there will likely bring 1500 credits, look at all those options, and attachments."

Despite the fact that the player wants it to be a "secret looting", use it as a scene that we, as the audience (if it were a film) and the rest of the players (as co-audience) see.in game. He might do this a few times. Then ween he goes to market to sell...

Later, the Character is speeder-jacked, robbed and beaten up, because he's known to be "that guy that always carries a stash of guns. Only this time, we're not paying him."

He's dealing with gun runners and smugglers and stolen gear, he also gets it stolen from him. Now can he step up and say "um, yeah I had a load of guns worth 20,000 credits. And I need help getting it back."

"when did you get all these guns?"

"You been robbing from us?"

Because as it is, he's stealing from the team, yet sing the teams firepower to protect him.

I saw this in D&D a lot, where a thief guy hogged all the treasure. He gets into a fight, and he's down to his last hit point.

The neutral cleric who normally cure everyone at a touch, says, yeah, that's "5000 gold to heal you today, I know you are good for it."

Something like that.

Utilize the in game consequences of everything, not just kill someone take their stuff sell it at the market, rinse, repeat.

This is why old guys and ladies used to get mugged on social security payday, before direct deposit. they'd go to the bank and be headed to the store to get groceries for a week or two. The people robbing them knew what day it was and set up for an easy payday.

Not that that still doesn't happen, but I'm just saying have in game consequences, not just I am GM no you can't have.

I once ran a Traveller game where a Noble had a ship out of control, headed for the ground of a local outpost world on a diplomatic mission where the PCs were bodyguards to augment the house troops. The ship had some suits of battle armor aboard. the noble got killed, with no heirs in sight in the subsector, , the ship crash-landed but was a write off, and some PCs got hurt, but nobody killed.

The players ambushed the few remaining troops aboard, made it look like they died in the crash, salvaged what they could, set the ship's drive to detonate, and took off in a crawler. They had all these suits of battledress, from the House. One of the players said to me, exact words "You should not have put the suits on the ship if you didn't want us to use them."

It wasn't about using them or not or having them or not, it's about choices and consequences. If the characters had quietly slipped them out of the subsector change configuration, and sold them on the black market that's one thing.

What they instead did was:

They donned the armor, ad went to the local towns and cities of this relatively small world, started robbing banks, making it look like the House Troops (that they had murdered) had survived the crash, and had gone renegade. Murdered local law outside the port, shot up APCs and ground cars, lit buildings on fire, blew up fuel dumps, creating a real chaotic situation, that the locals just were not prepared for. Then, they got the idea, well hell, we will demand tribute and set them selves up as technologically elevated god king dictators. It started getting really nasty, where they wanted to start having slave women and such, picked from the local populace, and tried to take on the local Marines at the spaceport who held them off, with equal weapons and gear. But the call went out to the Secotr Duke that the planet was in Civil war, and nobody was paying taxes because "Everything is on fire from the forces administering this coup".

Then after some weeks, the remaining real house troops showed up from a mission some distance away, backed up by Offshore Orbital Gunfire of a pair of frigates, and set them straight, killing half the party, while the rest fled for their lives, vowing never to return, with bounties on their heads.

I always try to go for cause and effect consequences where possible.

The players ambushed the few remaining troops aboard, made it look like they died in the crash, salvaged what they could, set the ship's drive to detonate, and took off in a crawler. They had all these suits of battledress, from the House. One of the players said to me, exact words "You should not have put the suits on the ship if you didn't want us to use them."

And as a GM, on the inside, I would have been grinning like a gooddamned schoolboy on prom night, thanking the gods for delivering unto me this grandest gift of them all.