Feeling Comfortable in a relationship is crucial. Either feeling comfortable talking, hanging out with, going on dates or etc. These steps will help.
Get to know your partner, maybe ask them questions such as their favorite color, foods/candy, sport and team, music tastes.. etc. Once you know the basics you can start to feel a little bit better.
Next, Make sure your relationship is open and trustworthy. If you're having a bad day make sure you can talk to your partner openly about it. Also make sure you are able to open up about past-relationships to your significant other
You need to know how to have your relationship and your friends relationship. Do not bring a friend on a date. And do not talk too much about your friends to your partner. And do not obsess over your partner. You both need to have your friends which you can hang out with and then other times just you and your partner.
Communicate. Be sweet and mushy but don't be a constant jokester, this can be tiring and there will be situations that require maturity.
It's a good idea to get to know your partner's friends. Be sure not to but in on their friendship or flirt with their friends.
Last but not least, Share a couple secrets about yourself that wont freak out your partner. A secret that can be told, not one that will get you dumped. But if partner asks you, tell the truth and be honest.
Have patience: It takes time for a relationship to develop. So, it will take time for both of you to understand and know each other. Don't be too desperate. Talk to your partner as much as you can. Spend some time together doing different activities, it will help you to build comfort with each other.