In early ticks outposts are essential. Before ticks start rolling I like to have two outposts already built. From there on I see it as this:
1)If you can expand attacking outposts do so, without building any.
2)If you need to jump to a location to capture more, build the outpost.
3)If you're likely to lose more res (oil to attack and armour losses on the attack) than building the outpost, just build the outpost.
It all comes with experience. Obviously you wouldn't build an outpost early game if you're only able to capture one outpost for it. It's all about judging whether the reward is good enough or not, and whether the competition around this selected area is worth travelling to, if you aren't able to manage it.
Making an op should be done with discretion.. Don't make ops often...
This I disagree with though, it's better to go happy with outposts, rather than have none at all.
Obviously late game you need to build the outposts to fill in the gaps across the map. This is easier though since this can be spit more across the whole alliance.
I'd say before tick 100 though I'd normally build 10-15 outposts and for each one I will get a much higher reward than the costs to initially build the outpost. I think what people fear the most is their CURRENT score. If you put that aside and think more about what you can achieve to get your LATER game score up, you will be more inclined to build outposts and will do a lot better.