Beltane, also known as May Day, happens on May 1 and celebrates the coming growth for the new year (this has a quite literal interpretation considering the holiday's illicit history!), as well as celebrating the importance of the sun; which is symbolized by fire.
Much like Ostara before it, greenery and flowers play an important part in your altar. Start with green cloth, candles, flowers, and herbs of your choosing; as well as incense such as rose, jasmine, peach, or vanilla and stones like rose quartz, garnet, and malachite. Make a flower crown (do hipsters still wear these?) Do a ritual for abundance in your life. Be sure to eat oats, but if oatmeal isn't your thing (and it isn't mine) try ginger apple oatcakes or rosemary oatcakes. And, if you're feeling adventurous, jump the Beltane bonfire.
Whether you celebrate on May 1 or not, I hope you have a happy day. Bye!
Picture doesn't belong to me