As with any custom experience, you must wear the outfit and not let the outfit wear you - in other words one is mere dress-up and the other apparel. Anything can become caricature and meaningless unless you establish its significance for the character.
Goggles (usually brass but sometimes from other metals. More aviator style than swimming or sports, the goggle reflects the daring open-cockpit, bi-plane, balloon, and airship dare devils.
A parasol serves the purpose of reflecting a more genteel time but also a real usefulness as a skin protection device. So too an appropriate walking stick. The epitome of classic Victorian and Edwardian adventure was the Pith Helmet. Gears, clockwork, timepieces can symbolize steam age technologies.
Those ideas in mind - explore some of the written works of the genre and get a 'feel' for the nature of steampunk and creative universe.