give them a reputation

It's an easy way to characterize, complicate and increase stakes. If society understands the MC as the resident good guy, there is more mental pushback when he has to make a morally gray decision. If society understands the MC as professional and put-together, there's more at risk when they lose their cool. It also easily contextualizes the kind of life they live.

worldview and personal experiences > personality

It's more difficult to figure out why a character is strong-willed and hardened than to figure out how being a soldier can affect relationships with other people. Prioritizing strong-willed and hardened might make you think soldier out of stereotype, but prioritizing soldier may make you think "Maybe they're weak-willed because they're exhausted of making the difficult decisions themselves" "Maybe experiencing such high stress gives them a lower barrier to what they can emotionally handle outside of duty" the possibilities are endless.

let your character contradict themselves in the process

There are always women who are misogynistic, intelligent people who fall for crypto scams, otherwise kind people who believe in hateful doctrine. I believe in environmentalism but get fed up sometimes, wishing my workplace would just give out single-use bowls so I wouldn't have to wash so many. It's a good way to add more depth and interest to a character.

the more insular and untrue their headspace and beliefs are, the better

A character who always listens to every point of view, no matter what, doesn't have much to stake upon. Even among the most accepting people are hidden biases they may not be conscious of. That can be an interesting point of contention, too--a character who is insular about how they're so accepting and objective, even if false.

listen to your character: don't shy away from natural progression

I have a bad habit of avoiding a character going in a certain direction. I'd had an idea since I created her in middle school that Erin probably experienced a form of abuse I didn't want to write, so I always tiptoed around it, trying out probably five different backstories that never clicked. Only within the past year did I realize I don't need to limit myself, and now, I completely understand her character in a way I'd been struggling with since the beginning! If you have any unconscious "rules" for yourself on what you can write and how you may write it, you may want to step back and think on whether they're truly necessary, or hindering your progress. Explore outside your comfort zone.

finally, some topics and questions to help think about worldview

Religion (What do they think of the religion they were raised with? What's their current religion and why? What do they think of other religions? Are they more judgmental of some religions than others? Do they follow religious customs, even unconsciously? How does their religion affect the way they see things?)

Gender (How strongly do they believe in the gender roles of male and female? Do they believe certain traits to be integral to men vs women? Why? How strongly do they believe in playing the role society wants them to play? Does it matter to them if someone thinks they've "failed" that role? Why? How do they feel about trans people? Even if they're trans themselves, is it possible they still have any biases on the matter?)

Romance/Orientation (Basically, what's their relationship to amatonormativity? Do they believe romance to be more special than other kinds of relationships? Do they believe romantic relationships are a prison? Why? Does it matter to them to be single for a long time, especially if others around them are in relationships? What is most important to them in a partner, if they want one? Do they use romance to replace something else missing in their life? How confident are they in what their sexuality is? How would they feel and react if their own sexuality wasn't what they thought it was? How would they react if someone else came out to them? Would they be accepting of some identities and nonaccepting of others?)

Sex (Does it scare them? Disgust them? Is it not a big deal to them at all? Why? How often do they have it, or do they have it not at all? Why? Is sex something they think about a lot, even if they don't act on it? Do they hold any misconceptions about it?)

Race (How does their culture inform their beliefs and the way they move around the world? Don't skip thinking about this because the character's white—white culture and its dominance inform things just as much. Think about where they live, the people they're around. What is their response to cultures outside their own? Curious, rejecting? Do they have to be careful doing some things that other people don't because of society's perception of their race? How do they respond to ignorance toward their race? Do they care about making sure people understand, or do they feel they're talking to a brick wall? A mix of both?)

Humans (What does your character assume all, or the majority of people to be like? What are some things they maybe assume to be human nature? This could hone how trauma affects their minds; a character with trust issues could think "It is human nature to be imperfect, therefore everyone must betray each other eventually, and I don't want to be betrayed")

^ Related: Friends (How easy is it for them to consider someone a friend? Do they consider the person they always make small talk with at pottery class their friend? Do they only consider them a friend if they know all their secrets? Do they think being part of a community is important? How does this compare or contrast to their actual involvement in communities—do they stick to themselves? How intimate do they believe friendships can be without being romantic?)

Politics (Do they pay attention to politics? Are they important to them? Why or why not? What are their family's political beliefs vs their own, and why are they similar/different? Did they once believe something different? Where do they get their news from? How conscientious are they about making sure things are true or not true? Who or what do they blame for societal problems?)

Work (Do they believe in the value of hard work? What did they want to be as a child? What do they want to be now, despite what they're actually working as? If they're not working the job they'd like, what circumstances keep it away from them? How much value do they put into having a good relationship with their coworkers? What about their boss? Have they ever received judgment for their career? How would they feel about it and respond to it if they did?)

^ Related: Finances (What class were they growing up? What class are they now? How do they feel and respond to being judged for economic status? How do they feel about those financially more fortunate vs less fortunate than them? Do they resent the rich or think they must be doing something right? Do they sympathize with the poor or think they must be doing something wrong? If they were given a billion dollars but had to donate it all to charity, what causes would they care most about funding and why?)

Family (Is blood thicker than water? Should children always listen to their parents and elders? What do they think is good vs bad parenting? Are they the oldest sibling, youngest sibling? How does birth order affect the way they were raised and the way they view things? For example, if they're an older sibling, do they take on a parental-like role for the younger sibling? Why or why not? How do they talk about their family members? Do they maybe talk about them in a way they wouldn't let other people talk?)