I don't want to sound like I'm talking about myself. But... I started playing last year when Jinx came out. I only played a couple normal matches a week until this holiday season. (Less than 300 wins.) Poro King mode and ARAM are fun and imo good for becoming more familiar with a broader range of champs. I didn't touch ranked until yesterday when I saw that the mode was now available for me. Something about having purchased my 16th champ I think. Went through provisionals and got placed Silver 4, completely bypassing Bronze.
Here's the important part. The provisionals were ridiculously bad. Constant AFKers, trolls, and really bad players. On the other hand, I had one match where the other team was clearly far more skilled than anyone on my team. It was hard to get a good game and I felt constantly frustrated with the mode. I wanted to say "Ranked sucks ballz. Going back to normals." But I stuck with it. Once I got placed games were a lot better. Or at least a lot more consistent.
I think what happens is a lot of people just boosh their way into ranked by buying a bunch of champs, rushing 30 in bot games using their favorite OP champs, and then "Imma 1337 pilot!"
If I can humbly offer 2 pieces of advice, they are stick with it, and ward everything. You can never have too many wards.