First of all, you need to understand that there are many different types of groups. You’re not going to fit in with every one of them, and you’re not going to feel comfortable in every one of them. They’re not all going to feel comfortable with you. That’s part of life, and it’s part of the seeking process. Some groups may have a dynamic that just doesn’t work for you – if you’re a male Wiccan on a Celtic path, then an all-female Greek Reconstructionist group is not the place for you.
Some covens are limited to males or females only, others are specifically for gay Pagans, and some are for families and married couples and exclude single members. A coven you’re interested may already have what they consider their ideal number – sometimes thirteen but frequently less – and they may tell you to wait until someone leaves before you can join. Accept this, and move on. Don’t take it personally. Ideally, you’ll be able to find a coven in which you can get along with all the existing members, and you won’t have a clash of personalities or philosophies.
Also, realize that a coven is like a small family. Many Wiccans are closer to their coven-mates than they are to their own siblings. Just because you’ve found a coven doesn’t necessarily mean you are guaranteed acceptance. Coven membership is a two-way street. Wiccan covens do not actively recruit new members, and no matter how uber-witchy you think you may be, if one member of the coven has a problem with you – justified or not – it could keep you from becoming a member. Take the time to ask questions when appropriate, and you can make an informed decision in the event that membership is offered to you.