I got OCD when I was a little kid and my brother died. It's taken many forms over the years, hand washing to the point of barely having any skin left. Having nighttime rituals where I had to repeatedly say the names of everyone I cared about because I was convinced they would all be dead by the morning if i didn't.
Checking things, doors wallet, anything really. Constantly redoing things I'd just done because I needed to confirm I'd done them. You name it, I did it. The intrusive thoughts that came with it were even worse than the constant rituals.
I managed to overcome it in my early thirties. It wasn't meds or therapy for me, I'll be really honest with you, it's having to break the cycle, like a previous poster said. Work on one ritual at a time, if you have to check the door constantly, just don't get up one night and do it. The anxiety will be through the roof, but when nothing happens, you come to realise it doesn't matter so much.
If it's hygiene related, force yourself to not scrub your hands. Leave the dishes in the sink etc.
I know I've probably made this sound far more simple than it is, I know it's not easy, I spent so many years basically scared to do anything. But once I stopped the rituals the intrusive thoughts quietened so much