Basic Mechanics
Ahh, the much-maligned galaxy (or supply) event. Yes, it's true that these use your resources rather than letting you accumulate them like you can in other event types. In these events, you will use your precious inventory to craft recipes and then turn those in for VP points. They are separated by two phases, in which VP will ramp up each time.
It's a common strategy for those looking to only clear thresholds to begin the event in phase two so that they can save the need to ramp up twice. It’s more efficient, and if you don’t have an event character already, it will also allow you to wait for the community rewards to hit so that you can get some event crew and level them. Be mindful of which items are in thresholds as you level, though. I’ve had to chuck many a gold uniform into the replicator for getting overzealous.
Please see the tables below (info from the wiki) which show the values of points for missions and super rares in each phase:
As you can see, the scaling is also friendlier in phase two, which is another reason why many people will choose to wait.
Some recipes have a higher chron cost and want more hard-to get items than others. When a "bad" recipe shows up as a build option, leave it there. While the recipes will keep cycling through, anything you have decided to hold as an option will not cycle. You can use this to avoid recipes you don't want to build, either due to cost or due to low inventory.
Rare Rewards
Using a character to craft will earn you a chance at rare rewards, with event crew and bonus crew having higher chances. The chances are cumulative - if you fail to receive a rare reward on a recipe, your chance will increase next time the recipe rolls around.
'Bonus crew' is pretty unhelpful in galaxy events (5x bonus). There's no use in unvaulting all variations of a character in advance - just unvault event crew (10x bonus) if you have any, and then check the recipes for traits / skills that can be filled by your vaulted bonus crew. As previously mentioned, if you don't have any event crew, you may find some use in waiting for the community rewards to drop, and then leveling the event crew - or at least the one from the thresholds that you can be pretty confident you'll clear. Also, anyone you stick on shuttles or voyages will be locked out, so take care in not putting your top crafters on those.
Crew sorting is also an issue in these events. Often, the character with the highest chance of crafting a rare reward will not show up first in the menu. It’s usually a few points difference, so you may or may not want to click through and see who your best crafters are for a given recipe.
If you're just going for thresholds, there’s no point in holding rares. If you're trying to rank, however, you should be holding all rare rewards until the end. Usually, you'll see massive point accumulation on the leaderboards in the final hours of the event. This is from players holding and dumping their rare rewards, so you should be doing the same as well. As we’ve covered above, rares are also worth more in phase two than in phase one - although not by a huge margin.
Prefarming
When it comes to events where you can prepare in advance for a top finish and reach that without spending, galaxy is still king.
DB is super lazy. We all know that. In galaxy events, it works in our favor. DB reuses the same recipes every event, so it's possible to prefarm for all of the items that will appear in galaxy recipes.
There’s a great community spreadsheet that lists the recipes and components used in galaxy events here: https://docs.google.com/spreadsheets/d/1KiRTr3ri6BQBIdOVgKbckqA2iQu_hgWoIS3pPYLmDog/edit#gid=0
We tabulated 55 full galaxy events from that workbook and developed a singular farming list based on the frequency of components appearing in those events, which can be found here: https://docs.google.com/spreadsheets/d/1pdw2_mgn1jDF_5VzfOuUP4p5frzZsSTDpZT8cknu35M/edit?usp=sharing
While the full info is in the workbook link above, when in doubt of what to stockpile, focus on these:
You can also use the following workbook to upload your inventory from DataCore and see a suggested farming list, based off those tables (same workbook as in the skirmish section, just look at the Galaxy tab): https://drive.google.com/file/d/15lW1EZM-NZlFnMTynRTKwjl97nlZPJSz/view?usp=sharing
As stated above, frequency is a gauge of how often an item is used based on our study of items used in 55 full galaxy events. Items with the highest frequency appear most often in recipes across events. Yes, I know, you may disagree. You feel like events need a million of the red tip things (those are hyperspanners btw - #38 on our list). It's because of drop rates. The higher the item cost, the more times you'll have to search for it. Yes, you will need those too - but you absolutely will need more databases per recipe than hyperspanners.
And last but not least, anytime you're running lots of missions to get items or level crew, always use a supply kit!