Aside from wrapping any fragile ornaments and packing them in groups by similar, size or colour, a quick tip is to use an empty liquor box or beer case. Those nifty dividers help to keep items separate and protected and they are free at your local liquor store.
The other advice is getting the lights put away neatly and to replace bulbs NOW to avoid delays in setting up next year. I always keep a spare identical string of lights on hand. Especially those half burnt ones with the other half of perfectly good lights! Waste not want not! I've finally gotten around to getting some videos done to demonstrate . (yes I'm in my onesies) Consider them late Christmas gifts from me to you!