Outside of Paganism it tends to be the case that you go along to religious gatherings as an observer. The audience/performer dynamic between priest and assembly reinforces the idea that you’re mostly there passively, to have something happen to you. When people first come along to Pagan circles, it can be easy to assume the same thing is happening. Often one person appears to be leading, others may have roles, and you as newbie are just an audience. Wrong!
To get the best out of a ritual, you need to start by taking yourself seriously as a participant.
It’s not a block of audience, most usually it’s a circle, and each person in that circle is at just as key a point as any other person. The focus, presence and intent each person brings to the ritual, matters. This is as true in loose, open circles as it is in more intense and closed magical groups. Everybody counts.
Often the idea of dressing right and knowing what to bring seems more of an issue to people in advance of their first ritual. Most Druid circles don’t require people to dress up, especially not the first time, so the right answer is usually to be dressed for the location and likely weather conditions. Most Druids prefer to work outside, so a decent pair of boots and a waterproof coat may be the best ritual gear available!
If the person or persons leading the ritual are any good at all, it will not be a problem that you as a new person do not know how things work. I would say that a group accepting the inexperienced but unable to look after them is probably not somewhere to go twice.
If you are serious about Paganism and not just going along to observe (which is fine to do in many situations) then you need to participate to get the best out of a ritual. Most of this happens in your head and heart. It is about being open to what’s going on. Think about what is said, let your emotions be stirred a little and your imagination stimulated. Treat this as a magical experience, a chance to connect with the awen and experience a flash of the numinous, and there’s much more chance of that happening.
What probably isn’t obvious when you’ve less ritual experience, is how much odds your attitude makes. Atmospheres in circles are delicate things, made up of everyone present. One person who isn’t taking it seriously, one person who isn’t really present, or concentrating or engaging can be enough to have a discernible, negative impact. At the same time, one really engaged person can shift a lacklustre ritual up a notch. It doesn’t matter that you’re new, if you are present, you have a share in how the ritual goes.
Rituals are far less about the words and actions than they are about thoughts, feelings and intentions. You don’t need to know the words to engage with the intentions, and if your heart is open to experience and you are willing to be moved, then even as a total novice you can play a meaningful part in a ritual just by standing there and giving yourself to it.