Been playing for 5 years, want to improve

I've been playing this game for a very VERY long time now and I've felt like I hit a slump as far as personal skill.

I was hoping if anyone would be willing to play a few matches with me and call out anything that I could improve on and point out things I may be doing wrong as well. I don't play ranked too much (less then 50 ranked matches from Pre-Season 1 till now) but at one point (season 4 if I'm right) I was placed S4 and climbed up to S1 but failed promos and kinda quit after that.

If it's any help, I have all champs, 14 rune pages (thanks for the free rune page btw Riot, I still remember!), and nearly every single rune with 10k IP to spare.