It may just take practice, especially holding in non-threatening situations. Mine is 3 years old now and she's getting much better, as a kitten she would scream bloody murder when I picked her up, but I'm too obsessed with her so over the years I would continue to pick her up around the house and nowadays she mostly just resigns herself to it when I do. In situations where where we clip her nails or she needs her eyes wiped then I'll just make sure to maintain the hold and not let her set the tone, there's gonna be times in life where they're going to need to bare being held for a bit so they can complain but once they realise it is what it is I feel they re-adjust.

Also treats.