Tip - onions
One thing I hate is cutting onions, so one thing I do now is do all my cutting at once, exp when I have a large bag of them.
Here is where a food slicer comes in handy, you can buy them fairly inexpensively, Rival makes a good beginners model that folds up for storage.
If you are planning on just adding the onions to a recipe, freezing onions is a good way to store them.
So using a slicer, v-slicer or a good sharp knife, take your peeled onions, cut off the ends and slice them. Take small sandwich bags or freezer bags and portion the onions into them, label and simply store in the freezer until needed. Freezing does break the walls of the onion cells, but since they will be used in soups, stews and recipes where you don't need fresh sliced onions this is a good way to make sure you have what you need handy and not have to chop onions each time.