dont focus on your stats so much, especially starting out (bad habit forming). there are lots of resources here and on yt of stream vods of the best soldiers, whether that be on their respective yt channels or channels like officerreekz and fresher+cleaner
if you really want to see the biggest improvements, playing on an actual team to learn the fundamentals with others helps a ton. if you have watched comp tf2 streams before, I'm sure you know about RGL and/or ETF2L (not sure about your region). I'm sure other people on here can fill in the gaps on what I've missed in this post, but I think this covers a good portion of the point.
also don't sweat being a noob too much since we all were at one point.