I think that a good strategy can not be executed without proper tacical skills so if ou want to improve your rating try to emphasize tactical training. However, I think the most important thing is to do whatever you think is fun, may that be strategic studies, openings, or rating improvements.
Tactics Trainer or Positional Strategy?
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I think you should study both. But I think you're also correct when you say that studying tactics is probably going to win you more games by far. You can pretty much guarantee anyone below 1700/1800 level will give you a chance to tactically win something if you play a solid game and don't give them many oppurtunities yourself. I'd probably say don't let up on the positional stuff though, I don't know much about it but I wish I knew more. I get far more satisfaction now from a win due to a strategy I came up with that actually worked over a game than an "exciting tactical combination".
And here's what you need to know about openings/what I know about openings 
- Get your pieces earning their keep
- Make sure your king is safely castled early on (unless you have a very good reason)
- Try and control the vital centre squares with pawns/minors.
if you all want to do is play blitz and/or bullet on the internet just do tactics. it'll be fine. silman's books, I think, are mainly intended for people who play in otb tournaments with 1200-2100~ ratings
I have been playing chess seriously on and off for a about a year and a half now and I am completely determined to improve my game. I read one of Silman's chess books and I think that it quite helpful for learning the basics of positional strategy; however I did not notice much improvement in my rating just from studying the book. What I do believe has boosted my rating noticeably is diligence with the tactics trainer.
Anyways, my question is when do you think I should shift my focus from the tactics trainer to Opening/Positional strategy? My original thinking was that I would let up on the Tactics when I got my TT rating to about 2000 (I'm at 1700ish right now). I'm not an OTB player really, at this point I mostly just care about my blitz rating. My knowledge of positional ideas I think is okay, but my knowledge of opening strategy is effectively naught.
Any thoughts would be much appreciated. Thanks!