Ah the protagonist, the main character of your epic adventure. Whether they’re good or bad, human or otherwise, they’ve got a goal and that’s why this story even exists. Without a good protagonist, the story just falls flat no matter how much effort you’ve placed in the plot. So here’s some important things to look at while writing and designing your main character.
1. They've got to be relatable.
Now, this doesn't mean that they have to be an actual normal human being. They can have some remarkable super power. They can even be some sort of alien creature. As long as they're relatable in some other way. Do not make them perfect. They have to have their faults, or readers won't be able to connect with them. Make them forgetful, or reckless, or unable to spell simple words. Something that makes them seem more realistic. No one wants to read a story where this perfect person goes out and saves the world in a perfect way and then comes home to his/her perfect life. It's boring. Make a character worth rooting for.
2. They have to have a reason to be in this mess.
This story of yours is probably going to have lots of twists and turns, so what makes your character want to stick around and keep fighting? Sometimes they don't have a choice, and these things just keep happening around them. I think that's a cop-out. Every human has a reason to do what they're doing. What makes their will to keep fighting that strong when they aren't even sure that this is the last time they'll need to be that strong? Is it for love, revenge, money, hope? Do they just have a strong moral compass? You need to give your character something to keep fighting for. Otherwise no one would blame them for giving up.
3. They can't be one dimensional.
Human's aren't simple creatures by any means. Don't make your character any different. (This goes for not only your protagonist, but every character they meet along the way.) In this world that you've created, you're only telling a small story. You need to imagine what's going on in the rest of the world around it. What happened to your protagonist before this story began? When a character is no longer relevant to your story, that shouldn't mean they disappear. I know in reality you probably just dreamed them up from nowhere, but if you give them a beginning it goes a long way with making them seem more realistic. Give them stories of a time before this book began. Give them traits they picked up from someone who may not even be mentioned beyond it. Make them real.
4. They can make mistakes.
Being a protagonist doesn't make them above anyone else. It doesn't even mean that they have to be a good person. Your character can still be tempted by greed, lust, money, and a ridiculous amount of other wonderful temptations that litter our world. Depending on how strong their will is, they may even give in to some of these temptations. If that's the case then overcoming those temptations may even turn into a narrative conflict of its own. One that readers can relate to probably a lot better than saving the world.
5. They don't all have to have a freaking love interest!
I cannot stress enough how annoying it is that every book I see nowadays end up with the same lovey-dovey ending. Create a character who the reader is rooting for more than they're rooting for this unnecessary couple. Now, this doesn't mean they can't end up with someone, if it happens to flow with the story. But in reality do you think they'd be more focused on their goal or finding a date? It it happens, let it happen. But never force it. The reader can tell the difference.