Help I wanne collect tho but don’t know where tho start

My best advice is if there are any physical shops near you that sell dvds (sometimes they're sold in cd stores or thrift stores, sometimes even antique shops) and see if they have anything you've seen and know you like. compare prices. see what you can afford/are willing to pay. if you've been wanting to watch a show or something, see if its at the library in dvd form and watch it that way before committing to buying it. or, if you want to risk it, buy it before watching if you think you'll for sure like it. there isn't really any elegant place to start, nor is there any 'right' way to do it. Just think of what you like, pick something that's affordable, and boom. You've started collecting. 

just start with your favorite movies and shows, especially ones with limited streaming availability.

And I second the comment above, most thrifts stores have a big variety, just make sure the right disc is actually in the box