Examples :

Person A : Wedding arrangements done ?
Person B : Not quite, I still have to fine-tune a few things.

“Leandro, our football coach, tends to spend hours fine-tuning his game tactics. They call him the new Guardiola.”

Examples :
- “My husband picks up his socks from the floor once in a blue moon. That’s why I’m divorcing him.”
- “I only check my gmail account once in a blue moon.”

I don’t completely agree with you on that."
completely : although this suggests you agree to a large extent, it usually means the contrary
"I really can’t agree with you on that."
"I can’t say that I share your view."
"We’ll have to agree to differ."
we’ll : a convenient way to stop the argument if there doesn’t seem to be any way to reach agreement on the subject.
"I’m not totally convinced by your argument."
"I can’t accept your point of view."
"I can’t help feeling that ..."
"I feel I must disagree."
"I really must take issue with you here."
issue : argue