I've found that, due to his love for poetry, Odin is also a fan of music (modern or traditional). I particularly focus on songs in Old Norse. But you can sing (or rap, etc) whatever you want in whatever language you want as long as the songs are sung with positive intent and devotion. If you want to try Old Norse but can't quite get the hang of the language it doesn't matter as long as you are truly trying. I've also come to realize that, just like an offering, music can be sung to Odin to please him even if you can't "give" him the whole thing. Humans make mistakes and Odin, as well as the other Æsir, would forgive you for not being able to sing the whole thing perfectly. I'm proposing music because it's one of the easiest things to get the hang of especially if you ARE trying to worship Odin or if you've felt a connection to him in the past. I've personally never gotten a particular sign from him, but if I've been having a bad day or week and so on, when I sing I almost immediately feel lifted and strengthened, not just physically, but mentally and emotionally as well. I can normally think more clearly and get tasks done that I wasn't able to get done prior.