All religions can be said to have one thing in common. There is always an idea of the mystical experience. Unfortunately, due to prejudices, social norms, and advances in psychology, most of the time, these mystical experiences come off as bouts of insanity. Yet in Buddhism it's enlightenment, Zen has the perfect state of everything being in harmony. Abrahamic faiths have interactions with their deities, and those pure moments of faith in the impossible. The Upanishads has an understanding of Atman. Or, if you're really thinking, the idea of the One, and a weird interweaving of everything, but I find some of that hard to grasp when placed in comparison to some of the older religions like Greek (though I can sort of see it with Greek mythology) and Norse. If anyone has some free time, I recommend the Gospel According to Thomas (One of the books left out of the bible), because it's amazing as to how some of the passages sound like they came from Buddhist/Taoist texts.
Anyway, what my point here is, is that most religions have a few things in common. Ways to live, why to live this way, and a structure of beliefs to help guide people on this path. What most BM religions have, is deities, what they did, a creation myth, and an afterlife. There's so much more to it than that. If you can answer those three questions, you'll have a more fleshed out faith.
Also, while holidays are nice, most of the old religions (before a lot was phased out), apart from sacrifices, used toxins to bring themselves closer to their God/Gods. Even now, Christianity still uses wine, but drugs, alcohol, and special preparations of plants were quite common. Communionism was onto something in FEI when they used Ikrif to speak with the dead.
Also, a lesser known fact, that's commonly confused, if you're looking for an idea... Devil names, such as Lucifer, Satan, Beelzebub, etc... aren't all the same person. In actuality, each is a separate fallen being, and is considered a Prince of Hell in their own right. There are seven, one for each sin. Satan is wrath, Lucifer is pride, Beelzebub is gluttony, etc... etc...
I don't really have the time to spend developing a religion, but I'll be glad to help out if you need some small ideas from time to time.