@GGrimes Here are some things you can do:
Search for hashtags of things you are interested in.
Pin columns of hashtags you are especially interested in, such as #linux, by clicking the hashtag, and then clicking the three horizontal lines with dots.
Send out an introductory toot that includes the hashtag #introductions plus all the things you are interested in, like #cats #mathematics #chocolate #gardening #amwriting #amreading #mastoart