My first clue is how I feel about my husband. That's how my therapist can tell if I am going up. If I am feeling dissatisfied, irritated and generally not saying much good about him, that's the first sign. (also how many times I hit her plant with my hand while talking...it sits right next to the chair)
I get more energy.
I sleep less.
I get hypersexual (I've only acted on it twice, once online before dx, once in person a few years ago)
I write, poems, stories, journaling. Pages and pages.
Talkative
Restless
Confident
Joking
Talk a lot with my hands

I haven't had a purely hypomanic or full blown manic episode in a while though. Mostly mixed these days. yuk.