Knobs and handles can really give life to something that once was just there. The tiniest change can make a big difference like when I decided to add some cool handles to our guest room closet door. It's a hollow door so there was prepping to be done.
I took off the little "knubbins", (I don't know what else to call them).
Maybe boring finger holes?
• Filled the hole with wood putty (left image above)
• let dry over night
• sanded it smooth
• put a coat of paint over it
• drill holes for handles, insert a plastic anchor (right image above)
• insert screws
Voila! The closet door handles now help make a cohesive theme to the room. The handles were less than $2 each by the way at Loews!