What to talk about in conversations?

So ive be talking to a girl for a bit(she txted me first)and its been going ok but i just have no idea what to talk to her about.we do all the normal small talk stuff like good morning and asking about eachothers day but its just the same things everyday. We dont really have many common interests other than smoking weed 😓. I just want sum advice on how to add some variety to our convo. I rilly want this to work out so this is kind of my last ditch effort posting this here. Thanks for the help and sorry for bad typing and format