I actually find it easier to write about sweet/adorable characters. Maybe because most of my friends are sweet and adorable, and I’m very much that way myself (or not.) But anyway, the thing to remember is, even the best people–the coddling grandma, the sensitive husband, the devoted mother–have their flaws, insecurities, inconsistencies. The combination of love and impatience, courage and fear, thoughtfulness and criticism, is what makes your characters seem real.
I have several adorable characters that I hope I’ve humanized effectively. The main one is a young woman named Kindra Arden. She’s a tiny 4’11” with rapunzel hair and a bubbly personality. She also owns a 18-hand Shire stallion named Binky and a rambunctious cat named Mittens. Kindra is also a (non-practicing) witch and a first responder (EMT). She acts so friendly to avoid thinking about the things she’s seen at work. When faced with a medical emergency the buoyant cheerfulness dissipates and is replaced with grim seriousness. So while she is quite cute and adorable, that isn’t all there is to her.
"Remember, you go nowhere by accident. Wherever you go, God is sending you." - Rev. Peter R. Hale
I think what everyone else said is true. Creating a good character isn’t about personality, it’s about (as Abbie Emmons always says) internal conflict. If you can create believable emotions, you can create believable characters. It really doesn’t matter what they’re like otherwise, or how “different” they are, if a reader can relate to their thoughts and feelings.
Making a character amazing and adorable can be super hard…one tip might be spending time with someone you think is amazing, and then trying to use some of their phrases, hand-motions, facial expressions in your story.