So many juices.. it's so overwhelming when you're just starting out. It's really trial and error, and you'll quickly learn what you like and dislike, but keeping in mind that over the first few weeks your taste buds change significantly, and what tasted gross to you in the beginning may not be so bad after 2 weeks (or vice versa). I started out loading up on chocolate and coffee flavours, because those are my favourite things

But, just as I dislike actual flavoured coffee, it seems that extends to e-juices as well. Just, no. My first purchase was Halo juice (because everything I read said they were the best) and I got the Shamrock and Cafe Mocha, and a couple others. They are now sitting at the back of my stash, used only a couple times.
I like the fruit, but it can't be too sweet. Something mildly fruity with just an underlying hint of mint seems to be my sweet spot. I'm also not keen on the dessert'y ones. I don't want my vape to taste like cinnamon apple pie or blueberry cheesecake, but some might like that. I also don't want to taste any amount of tobacco, because that's the biggest reason I wanted to get off analogs, I hate tobacco taste. Right now my favourite juice in the world is Hawk Sauce by Mt. Baker Vapor. I can vape that all day and night and not get sick of it.
Sample sizes are a great idea, and often you can get little 10 or 15ml bottles, just enough to see if you like it or not before you invest in a bigger bottle. I'm a little over 2 weeks into this and have probably 20 bottles (big and small) that I am working through, deciding what I like and don't like. Ideally, I hope to narrow it down to 4-6 that will be in my regular rotation.
Happy experimenting!