Sometimes you are not meant to like the protagonist right away, and there are many varying ways to produce a likable character. But most of the time it is a very good idea to make your main character admired, or at least respected, by the readers in the first 10-15% of the book.
There is an excellent example in Jamaica Inn, Daphne Du Maurier, that I personally appreciated on a huge level, and made the entire book more enjoyable because I knew almost immediately that Mary Yellen was someone I could root for and admire no matter what happened.
CREATE A SINGLE, PHOTOGRAPHABLE MOMENT
After the death of her mother, Mary goes to stay with Aunt Patience and her husband, the land lord of the notorious Jamaica Inn. But upon arrival she is revolted by her uncle, the horrid inn and the altered character of the happy, silly aunt she remembered.
Mary is resolved to leave that very night. But the moment she steps out of her room she hears the wretched, tormented sobbing of her miserable aunt.
Mary does not hesitate. She realizes how terrible her aunt’s life has been and she immediately changes her mind. She resolves to stay and bear the torture of Jamaica Inn if only to rescue her aunt.
Daphne Du Maurier’s lyrical and expressive prose describes this moment beautifully and poignantly without stating the obvious or telling. Every moment is shown and you are completely drawn into the horrible world, experiencing first hand Mary Yellen's emotions.
One precise moment in the arc of your character can make or break the readers' relationship with the main character.
A respected character not only makes the story more enjoyable, it strengthens the bond between character and reader and makes it all the more memorable.
SO. . . HOW DO YOU DO THIS?
This part also serves as Mary’s “point of no return”, the moment when there is no turning back, and the heroine takes on the plot in full force.
Step 1: Create a moment in your story where your protagonist must make a defining decision, ideally between two negative alternatives.
Step 2: Make this decision an important deciding factor in whether or not the protagonist will go on. That moment should instantly define them and set them on a course about which the entire story is about.
What is your protagonist's moment of no return? Will readers' love 'em, hate 'em or admire them from afar?