It depends on whether you want to write longer or shorter. If it's longer, choose a poem or song that you like. You don't have to write the whole thing. Just cut out your favorite fragment and write it. The more commonly written ones are "Spring Snow in Qinyuan", "Yong Yu Le" by Xin Qiji, "One Cut Plum" and "Like a Dream" by Li Qingzhao, etc. You can look for them, even the poems you have learned in your textbooks. It couldn't be better.
For shorter ones, you can find famous quotes, aphorisms and the like on the Internet. It's like "There are roads in the mountain of books, hard work is the path, and there is no limit to the sea of ??learning, and hard work is the boat."
As for the materials, it depends on whether you are writing brush calligraphy or hard-pen calligraphy. For brushes, you can use either familiar Xuan or Xuan. It depends on which paper you are more familiar with. Generally, it is better to be declared alive. You can go to a framing shop to simply frame it and then hang it on the wall.
If you are writing hard-pen calligraphy, buy regular hard-pen calligraphy paper, most of which can be found on Taobao. After writing, you can simply paste it on black cardboard as a background.