The top way to attract Hummingbirds is nectar (sugar water), which can be purchased commercially or made at home. It takes just two steps to make it at home:
Mix 4 parts boiling water with 1 part refined white sugar, until sugar is dissolved.
After letting the mixture cool add it to nectar feeder.
Orioles will occasionally consume nectar as well – though they prefer nectar that is less concentrated than the Hummingbird Recipe above– if you are most interested in attracting an Oriole with nectar, use 8 parts water to one part refined white sugar. If you make too much, simply store excess nectar in the refrigerator where it can remain for up to two weeks. Avoid purchasing or making nectar with red dye – as it may harm the birds.