People are hard to figure out, so making one isn't the easiest task in the world. Heck, it's pretty dang hard, but doable. I believe to create a good fictional character you need to know everything about them; their personality, flaws, thought process, hand gestures they tend to make while talking. If you haven't read a John Green book, then I suggest you pick one up right now. His characters are so original and real and captivating. John Green put a video on YouTube explaining how he does it (see link at the end of the post). Basically he said that characters in books are not built on images, like in movies or TV shows, but they are built on words. That being said, it doesn't matter as much as what they look like as it does on how they think.
Should my protagonist have flaws?
Yes, yes, yes and yes. Protagonists who are perfect tend to be boring and unrealistic. Don't give them just one flaw, because that too is unrealistic. Humans will be humans with hundreds if not thousands of flaws. Of course, you're not going to write down all those flaws because who has time for that. Write Five flaws as your minimum and Twenty- Five flaws as your maximum.
Should my antagonist have likable qualities?
The answer to that is yes. Just like your protagonist should have flaws, your antagonist should have some likable qualities that can appeal to someone.
How do I... Wha... I don't... I can't..
Yes you can! Creating people is hard, I know because they are so complex. You might be asking yourself
"I don't even completely understand myself, how in the heck am I supposed to create a new human being?"
Yes this task is tedious, but how else are you going to have a story if you don't have characters to have a story. Just remember to have fun with it, and if you aren't having fun with it, put down the pen and STOP WRITING (for a little while at least).
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~John Green Video
Hope this helped!