Slice them in thin even slices. If you’re using a mandolin slicer, go for the second lowest setting.
Pat vegetables dry (this applies mainly to potatoes which tend to be more wet).
Place vegetable slices in a bowl and add in olive oil (approximately 1 teaspoon per vegetable) and sprinkle with salt and pepper. Coat well.
Place slices on a prepared baking sheet. Being careful not to overlap them. They will shrink so they can be touching but not overlapping.
Bake for 10-15 minutes. Remove from oven, turn them over and bake for another 10-15 minutes until crisp.
Some slices may be ready sooner than others, so check the oven once you’ve flipped them every 5 minutes to see what needs to come out. When the crisps are browned at the edges and no longer shiny, they’re ready.