I suggest watching the StarbaseUGC tutorials. You need to learn how to use triggers.
And then practice, practice, practice. Start small and simple and then make them more complex.
I use them and they're a lot of fun.
I've been making heavy use of all the fun little things those tutorials bring. I'm just wanting to add the little things into the objective screen without making them imperative to completing the mission.
Unfortunately there's no way that I know of to get the [optional] indicator to show up in the player's mission objective list.
I've been including some optional objectives in my missions by dropping some clues to the player through dialog. So far I've received some positive feedback regarding them too. Optional objectives are a great way to add some dimension to a mission instead of simply leading a player through a "to do" list.
You can have a dialogue that informs them of the optional objective. Have it in the standard mission info green but list it as "Optional: Buy a jumja stick.
If your mission list objective is short enough you can also do this:
Go to Quark's Bar (Opt. Buy a jumja stick).
However, due to the length limit on listed objectives both the optional and non-optional objectives need to be pretty short for this to work.
Or you can put a few dummy objectives based on reach markers that trigger right away, followed by the real objective.
(Optional: Buy a jumja stick.) ^triggers right after the person moves from the spawn and a dialogue pops up.
(Optional: Get a raktajino from the replimat.) ^triggers almost immediately after they move again
Go to Quark's bar. (real objective)