When you are serving a dish in a large serving bowl, you can let it sit in hot water or if this dish can be put in the oven, put it in on 125 degrees F for 15 minutes before serving time. I also serve hot food on hot dinnerware, and cold food on cold dinnerware. I heat the plates in hot water or if I can, in the oven.
For summertime salads and cold foods I pop them in the freezer 10 minutes before serving. This works for me, I hope this helps you.
This is a page about keeping food warm at parties. You don't need expensive warming trays and steam tables to keep food warm at your next party.