I would say 1 of my mistakes was focusing TOO much on bringing in outside traffic instead of focusing on the current subscribers I have, which I did do but after my break I felt I just wasn't focusing on them well enough. I had to find a way to transition any beneficial changes I made to myself & my channel; to them.
My other mistake was not taking things easy, I let's play nearly everything (which is time consuming) and I legit ended up creating excel spreadsheets to manage my LPs & previews, I was noting down the completion times of the games, the release dates, and then prioritising them based off the information, then the numbers started to effect my prioritising (I'd look at a game and see "20hrs" and think stuff that) and it eventually overwhelmed me & lead to nothing getting played often. I still do manage everything via a spreadsheet but I've improved tremendously on that, categorised things better (I know have games I play for 1 off/random & games by release date as they're part of a franchise) and applied a more random-ish approach to everything I do with the channel, I now have a list of games I throw into a generator and I picked 5 randomly and downloaded them to play, I'll start off with a 1 off video and if it really catches my attention or if I feel like it, I'll turn it into a LP, otherwise if it's a game I generally don't feel like playing much I leave it at the 1 off. So I'm going through my backlog and it's great because there's games I've had for years & never played as well so that helps. I wish I had started that approach earlier. I even use the generator to pick what video I'll edit next xD
My other mistake was starting my first channel directed mainly towards friends and assuming they would be supportive & helpful. It was a beneficial mistake for obvious reasons though.
I've made other mistakes here and there but I can't remember them just yet.
embarrassing, considering I had everyone's name written down. I had to take down and re-edit and re-upload.