Well, it's really up to you. As far as the PAQ-era goes -- I would reckon -- it's just what
you think works. And
that, in turn, may be determined (when looked at most simply) by the missions and/or personnel you have available.
Let's start
from the personnel POV.
Put the personnel that you have, or like most (if you care more about that than winning -- like I often do), in a deck list by using the amazing
Online Deck Builder (did you find and use it yet?) and generate an overview / analysis. (Or count everything in e.g. a spreadsheet, if you feel old-fashioned.
) Now, you can easily see which, and how many, skills you have in that batch of personnel. You can choose missions to go well with those statistics.
A hypothetical mission that asks, say, Honor + Music (which you each have 2x) might sound easier than one that required Treachery x7. But if you're working on a Romulan deck, you might find you want to solve the Treachery mission, because you find that almost all personnel have that skill.
(Unrelated tip: Always insert some
extra "personnel types" such as OFFICER, MEDICAL, SCIENCE and SECURITY -- or generate them later, with appropriate equipment. You'll need them to help get through dilemmas. You'll also find that Diplomacy and some other skills are handy -- depending on the dilemmas you use for your other decks.)
Now for some slightly more advanced choices, coming in
from the mission POV...
You can normally win by doing, say,
3 missions of 30+35+35 points -- if you don't lose points! There are strategies that try to win with
only 2 missions that generate 45 and/or 55 points; and/or with added bonus points from self-seeded dilemmas (under your own missions) like
Sarjenka; or from "noun" cards such as
Particle Fountain. You can usually spot them easily by the point boxes. But some personnel, e.g.
Mordock, mention bonus points only in a special skill.
If you choose this line of strategies, you'll look at missions and then find personnel which can help do them.
You can divide missions in many categories -- two of which, are stealable vs. untouchable missions. Are there
other affiliation icons on the mission? Do you really want to run the risk that your opponent can do your mission? If not, in later sets there are cheap cards that can prevent that (
Fair Game). But you can also try to seed as many one-affiliation-only missions as you can, so that opponent cannot easily attempt them.
That, for now, should probably be the basis of your deck building. Play a few games and you'll start seeing new possibilities. Or -- stay here, first, and ask more, until you feel comfortable that you can go and buld the deck you have in mind. Just be patient with yourself and with the game.