One of the most important things is to make your characters likable. If they aren't likable people will not read your book. That's why making them real is so important. I like messy people. No, I'm not talking about slobs, though I love them too, I mean as far as characters go I like them to have problems, and misconceptions, and all those things that we have. Their situation has to be on the edge of change or there's no story.
But there is a reason why they are called the hero and heroine. We want to see someone who is flawed like us rise above the odds, their circumstances and the lies they believe about themselves and life in general. (And in a Christian novel, sometimes the lies they believe about God.)
How do you make a likable character? In must be in the opening pages. You have to make the reader care. The reader has to root for the characters. To do that they have to relate to them in some way. (Even the so-called villians. No evil just for the sake of being evil.) Sometimes it's their circumstances that we relate to and we see them respond in a way we want to.
Go ahead and imbue heroic qualities into your main characters. It's risky making the characters unlikable even for the sake of the story and some writers can pull it off. Look at Gone with the Wind. The heroine is never a perfectly likable character, she's selfish and full of her own ambitions rarely caring what happens to others. But we root for her anyway, don't we? Because in some form or fashion we relate to her.
In his book The Breakout Novel Workbook, Donald Maas says: More to the point, what is it that YOU find likable about htis character at this precise moment? Figure that out, and you will be most of the way toward making us, your readers, care as much about your protagonist as you do.
To find heroic qualities to give your characters, you may take a look at those people you find heroic. What quality is is that you find heroic? Give that quality to your protag and figure out a way to have her show something of that quality in the first scene. Then your readers will care about those characters if they like them.
That's not all there is to character creation. It's an ongoing and complex job, to create characters that are as real as you and I. There are their goals, motivations and conflicts.....but this is enough for now. I am learning right along with you.
If you'd like to, tell us about your character and how you've made them likable.
Happy writing...and reading.