You should be clean, yes. Washing your hair every day may be bad for some people but personally, I wash my hair every day and I've always gotten complimented on it. It's thick and healthy.
You don't necessarily have to wash your hair before every ritual, but you should take a shower because this shows respect and also ensures that we are clean both physically and spiritually, as we should cleanse our aura before a ritual if we haven't already done so that day. I hope what I've written helps you.