I'm an author who puts a lot of emphasis on character. Not only is character the most compelling element of most stories for me, it's also pretty important in the markets these days, where you'll see a lot of editors asking for "character-driven" stories. It's pretty important stuff, and so being able to convey your character effectively is extremely important.
My own concentration on character and on worldbuilding has led me to my current technique of using a character as filter and as conveyor of world (I'll discuss this more in my forthcoming article about last week's worldbuilding hangout!). That means putting a lot of focus on how my character judges situations and people and things, and quite often that means putting those judgments into internalization.
It helps if your character is generally contemplative, because then they have a lot of reason to share their judgments of things. Here's an example from an observant and contemplative character of mine, Imbati Xinta:
Xinta bent into a half-bow, watching a gang of six noble boys surround him. They had a new leader today: Grobal Rennerik, with reddened knuckes on his right fist that matched a mark beside the former leader's left eye. The followers' gazed flickered hungrily between them. Clearly this encounter was to become Rennerik's demonstration that his leadership was deserved. That would mean a difficult task - but if he could carry it out, he could prove his worth in love and loyalty to all of them at once.
Of course, you can have too much of this. If you have a contemplative character, try not to let them sit around and think without having anything going on around them (this is one of the ways a contemplative character can kill a story). In the excerpt above from "The Eminence's Match," I start with the arrival of the six boys, and give you Xinta's assessment of who they are and what will be happening next, and what it will mean. It demonstrates that Xinta is observant and also prepares the reader for the interaction which begins at the start of the next paragraph.
Ok, so far so good. But what if you don't have a very contemplative character, who wants to lay out his/her judgments and be super-helpful to the reader? What if you have a person who reacts and does things, but doesn't take the time to explain?
I ran into this with the protagonist of my current short story, "Mind Locker." Hub Girl is a kid on the verge of her teens who lives by her wits. She isn't contemplative. She has no time to sit around and think - but I still have to convey information about the world, the culture, etc.
Let me be clear. "Mind Locker" is in first person present tense point of view, capturing my character's thoughts direct from her head. Thus I do not mean that she has no internalized thoughts. I'm just saying she doesn't analyze them much. Here is an example:
We move out, fanning to circle the junk mountain. Hell'm I glad Fisher's by me - I message the others to make pairs. Soon the tunnels end. Careful feet here: glass, wire, ripped plastic toys. Further along, tires, fridges, dumpsters, burnt-out zipcars. And rats. Adspace's got a lotta crap to cover. I watch every gap, nudge closer to Fisher. Alarm might come from anywhere.
Hub Girl doesn't take a minute to assess a situation before she jumps in. But that doesn't mean she doesn't judge. Her dialectal choices give me opportunities to express judgment, and typically she'll add a word or phrase of judgment into what's going on, like "Hell'm I glad Fisher's by me," which is both telling the reader how she feels and motivating her next action, telling the group to form pairs. "Careful feet here" is a judgment that lets her tell us a little about what she sees near the junk mountain.
The end result is that the pacing seems higher, which is appropriate to the dangerous breakneck pace of the life she leads. I end up with very short opportunities to show her opinions and motivations - and that means I have to take advantage of them to the hilt. Sometimes that means spending a lot of time choosing a single word, to make it do as much as possible. An example of a single word that needed a lot of tuning was the word I use to describe the augmented reality that she experiences. Essentially it means she has the internet in her head, and that she can use it to change the way she sees the world around her. I first called it "aug-reality" (short for augmented reality, obviously) but that didn't seem right because it was clunky, and because very often "aug" is used to describe physical augmentations, when this doesn't have any of that aspect. The other critical aspect of this is that unless they bump heads, nobody can see what the other person has chosen to augment their reality. It's customized, person by person. I did a lot of brainstorming, and finally to take the words "custom reality" and blend them into a single term, "customality."
What I find is that when I can't use as much internalization, I rely a lot more on the surrounding text - the descriptions and actions - to convey judgments. Especially if you aren't working in close point of view, that's where the sense of character is going to come from. I thought Kij Johnson did this especially well in her award-winning short story, "26 Monkeys - Also the Abyss." If you'd like to look further at your options for more distant points of view, I'll point you to the analysis I did of Kij's story, which actually has comments from the author herself! You can find it here.
In the end, I find internalization to be a great tool for all kinds of jobs - worldbuilding, character building, establishing motive and drive, etc. However, not all characters support the same amount of it, and so it's useful to think through what your options are when extended internalization isn't possible (even contemplative characters get a lot less contemplative when there's action going on!). I hope I've given you some good ideas of how to approach the problem.