Has anyone made a butterfly or bee garden? Any advice?
My entire garden is intended to help native bees, butterflies, and all local wildlife. The best thing you can do is plant native plants. They're the best option to help native bees and butterflies. Obviously (to some more than others), native bee and butterfly species go hand in hand with native plant species, which makes it highly important to use natives if you intend to help native insects. Native plants generally refer to those that are native to your exact area, but I occasionally add plants that are native to other parts of the US if I find that they benefit the same species of insects/animals.
Gaillardia is one that is native to most of the US, but not my area. It greatly attracts bees and butterflies, so I added it.
Penstemon attracts long-tongued bees as well as hummingbirds.
Spiderwort is an early season bee-magnet.
Black-eyed Susan (Rudbeckia hirta) is another that attracts bees and butterflies, and they flower for months, so they're a reliable nectar source. Consider Purple Coneflower as well.
Milkweed is the host plant for Monarch Butterflies. So, not only is it a nectar source for pollinators, it's also the only plant Monarch Butterflies can lay their eggs on. I grow four different species, including the popular Orange Milkweed.
If you want the ultimate Monarch Butterfly magnet, consider adding Meadow Blazing Star (Liatris ligulistylis).
There are other ways to help bees, too. Leave dead stems cut at least 2' tall. Bees will use them to nest in as well as shelter in. You can also drill holes in logs and place them around the garden.