Definitely have your own hobbies. Make sure you have some space from each other and DEFINITELY don't abandon your friends and forget they exist.

I think this helps a person to not be clingy as they have a life outside of their partner

Plan fun things together. Try out each other's passions, my partner loves space. I've never been interested really but we went to the space centre and loved it. It's nice to share things like that with each other.

Just talk about things and communicate with each other. Don't sit and stew over stuff that bothers you but equally try and be compassionate and understanding. Also, if your partner is upset don't always blame yourself as often it's reasons outside of the relationship!

Hope that helps!