Hello! Hellenist here. There’s a few things that most every practicing person does in Hellenism:
1. Research. Theoi.com is the best for this right now. Read the myths, read the interpretations of the myths, read the arguments of the myths. Understand why this deity does this thing, and why this other deity is offered this thing.
2. Pray. This can range from ritual prayer to simply thinking to your deities. Tell them about your day. Ask them what offerings they’d like. It doesn’t matter. Don’t be discouraged if they don’t answer (or take a long time to answer).
3. Make an offering or two. I have posts on common offerings and devotional acts to Hekate, Athena, and Ares, but to make it simpler: Hekate is typically associated with things like candles, dogs, and ghosts; Athena is typically associated with things like books, armor, and crafts; and Ares is typically associated with things like coffee, meat, and weapons. You can go the traditional way, you can place something on their altar (or just a surface) for them, or you could offer things like acts (visiting a railroad, reading, working out) or your own things (food, drinks).
4. Speaking of altars, make an altar! Or a shrine. Generally, altars are shrines with areas for offerings. Use common correspondences (or don’t, it’s completely up to you) for their altars. Most people have offering dishes or plates, cups, candles, and photos. You can make an altar on your dresser, desk, a designated piece of furniture, in your closet, in a shoebox, wherever. Altars are very personal and ultimately it is your decision.
5. Meet other people who practice Hellenism! Tumblr and Reddit are good for this. Share ideas, ask for feedback, you get the gist. It’ll give you new insights and a community.
Please ask if you have any questions! And good luck!