Tattoos

So I’m sixteen and obsessed with tattoos. I have been since I was really little. I have so many different ideas that I want but I also am afraid that all the ones I want won’t look good together. And I know obviously I’m kinda young to be planning to be covered in tattoos but I have questions such as

Should all your tattoos have a similar theme?

Is it ok if they have nothing to do with eachother?

When you get older do the tattoos look weird? I don’t mean like 30 old I mean like over 40.

Thanks in advance for answering. Everyone in my family is against tattoos and so I have no one to really ask. Also I already have a small one on my finger. It’s a heart