I'll be honest, it's something I'm in the process of learning myself! It's tough! You want the character to bring value to the story, but you can't make them too likable.

The best example of me attempting this with a character was Trent. I wanted to give the reader a sour impression of him during his introduction. Now, he's the second most liked character, according to my polls.

All my characters have positive and negative traits. So with Trent, I "frontloaded" his negative traits, then slowly introduced the reader to his positive ones over time. I think it was effective, but there are plenty of other writers who have good tips on writing characters like you're describing.