Not trying to plug my blog like this but I genuinely think it can be helpful as it's filled with some of my general advice
https://www.chess.com/blog/KingsideCastleNotation/how-i-got-2000-a-guide-for-you
Congratulations on 1600 it looks like you worked hard and you definitely deserve it 
After being stuck at 1200 for a long time i decided last year, that i would start focusing on openings. I learned a full repertoire of English, Caro-Kann and QGD. But when i went to play games i found myself lost, when the opponent played moves, that i didn't know the answer to.
So what was my "aha" moment, that made me win a lot quickly?
I often watch YouTube and see GM's and IM's explaining different topics. Even though I do get something out of this, it doesn't translate quickly or well to the 1200 level. So my breakthrough was mainly these 2 things:
- I found a YouTuber who is 2000 rated (so no big IM or GM) who very quickly taught me the mindset of how to get much better positionally and always kind of know what to do next in most positions. I didn't even HAVE to use my newfound opening strategies (Pegasus Chess)
- I started studying some endgames.
These two things were literally all I was missing to unleash the potential I already had built while being stuck at 1200. Of couse this alone wont make you gain 400 rating in 2 weeks. But if you are at a plateu, they will absolutely give you a boost.
But yes i know. Growing your rating in chess takes a long time and effort. Nobody will get around that. But it's nice to know where to start, when you're feeling stuck!