As someone who was a first timer a couple weeks ago and was very scared as well, I would recommend maybe Poltergeist. The set was cool and I don't recall too many scares that get right up in your face. The white ghost thing that appeared several times was incredibly non threatening, basically just a puppet. There's a few clowns if that freaks you out but aside from that I didn't find it to be bad. Stranger things was also very easy to get through assuming you're a fan of the show. I did not get a chance to do seeds of extinction but I expect that to be fairly low key as well. Absolutely do not go through Dead Zone first (if at all).
It did get easier the more I went through. You kind of get used to the routine of them jumping out, and then leaving, nothing more. Also be aware that the audio is half of what scares you, so just expect noises. Scary Tales was quite good as it was something a bit familiar.