Destiny Points
If you all have access to F&D, whether you've played or not, you should understand about Destiny Points and how they work. If you do not, then stop reading here and go learn about them....
Now that you're back, here is how Destiny Points (or abbreviated as DPs) can be used: to modify a check, trigger a talent, special ability, possibly a Force power and more. One such use is covered under the F&D pg 36, Luck and Deus Ex Machina. This involves players coming up with 'facts', adding context to the game, and basically influencing the game on a meta level that their character might have no control over. The example given in the book has one player "remembering" that someone stowed a piece of needed gear on their ship even though no player specifically stated they did so. As players, spending Light Side Destiny, you can literally add in things to the game that your character hasn't specifically done or might have no influence over, like having a rebreather stowed on your utility belt that you forgot about until just now, or upgrading dice on a check to increase your chances of success.
Because players will be using Light Side DPs only, whatever you come up with cannot result in direct or indirect damage or injury or death to anyone else. Ex: You cannot use a DP to say that the maintenance crew forgot to patch a hole in a pursuing TIE Fighter's cockpit, so as soon as it leaves the mag-shielded hangar bay, it implodes and kills the pilot! But, it could be used to improve the Repair check of your X-Wing's astromech causing extra power to flood the engines with a boost of speed that puts more distance between your craft and the pursuing TIE.
Keep in mind, some things you want to do with DPs may be too much to pull off with one DP and thus would not be possible unless there were more Light Side DPs and more than one player wanted to accomplish the same thing. This kind of teamwork can be valuable and impressive and result in some fun things happening.
Dark Side: While players 'spend' Light Side points, as the GM, I have to spend the Dark Side Destiny Points that result when those Light Side points are spent. And whatever you guys can do with them, NPCs will be able to do as well. Nothing has the potential to make me (the GM) feel more adversarial because I will have to use the Dark Side points to cause you setbacks and difficulties just so you can get new Light Side points to spend.
One thing I will not do though is use a Dark Side point to counter or negate player use of a Destiny Point. If you want to use it to upgrade a skill check, I'm not going to turn around and use a point to downgrade your dice on that same check. Or to tell you that you 'remembered' incorrectly and don't have whatever gear you wanted.
There may be times where I say DPs cannot be used or wouldn't be appropriate, but I will not use them to cancel out PC use of them either. And, neither can I allow you to use your DPs to cancel out my use of the DPs.
Last point on this, there may also be times where you want to spend DPs, but what you want doesn't happen, or isn't possible, at least not like how you want.
A Han Solo example: Tied to a pole, Han spends a DP to try and blow out the flame the Ewok is trying to use to light a fire under him to cook him for dinner. That may not even be possible, but the distraction of C-3PO floating on a chair stops the Ewok from lighting the fire. Everyone gets to laugh at the visual of Han desperately trying to blow out a flame, but he's spared just the same even though he couldn't manage the breath needed in his position.
Frequency: F&D warns against hoarding Destiny Points to keep me from using the Dark Side points against players. And I'm firmly onboard with that. I will do what I can to discourage that because, as the book admits, that kind of meta thinking goes against the spirit and feel of the game. Its a give and take but it doesn't have to be spent in retaliation for one side using DPs. It shouldn't be retaliation that motivates using the points because I don't want us feeling like adversaries, they should be used to improve the story/game.
Ex: In Return of the Jedi, Han uses a DP to upgrade a Stealth check to get close to a Scout Trooper on Endor's moon. He gets within engaged (melee) range, but the GM decides to use a DP to have Han step on a brittle twig that causes a loud crack that alerts the Scout before Han can take out the trooper.
---That could be considered a retaliatory use of points, but it doesn't harm Han, only prevents him from making a surprise attack and the trooper is eventually overwhelmed regardless and that scene also doesn't discourage Han from trying something like that in the future since that could be seen as just bad luck and not the entire galaxy conspiring against him.
Same movie, but another example could be the heroes in the shuttle transmitting clearance codes for approval to land on Endor's moon. A DP is spent to make sure the code is valid and allows them to land. Darth Vader happens to be on the patrolling Star Destroyer and now with a Dark Side DP to use, he upgrades a Force Power to reach out telepathically to try and sense if Luke is on the shuttle when his power might not normally have that kind of range. Luke felt Vader reach out in the Force, but attempted to hide himself in the Force much like Ben did on the Death Star to avoid detection on his way to shut down the tractor beam. Vader maybe didn't sense Luke or maybe did, either way though, that dramatic tension could be cut with a knife! Vader though also had his decades of experience as Jedi Knight Anakin Skywalker, cunning hero of the Clone Wars, and that gave him the idea to let the shuttle land anyway just to see how things played out (and kill the boredom of waiting for Rebels to just show up and practically ambush themselves), plus if Luke really was there, so much the better...!
In short: Don't be afraid to use the points, and be willing to add to the game using them if something inspires you. If you are unsure if what you want to do is too much, you can always ask me and I'll let you know. Yes, I will use the Dark Side points, but it will be to advance the game/story. If you all die, the game is over and I'm done as much as the rest of you, so you don't need to worry about my using the points or abusing them. And don't be afraid to use them just to keep me from using them.