If you have the time to read, then The Little Book of Talent is worth your investment in time. The chapters are short, the author discusses how players improve not only their game but any area of their lives.
As for chess specifically, do the puzzles. Your eyesight will improve.
I think I'm getting worse
#1
"I hit a bad streak" ++ Whenever you lose a game, stop playing and analyse it first.
"I can't seem to win" ++ Do not try too hard to win, focus on not losing. Wins will come to you.
"I just blew a game where I was really far in the lead and victory seemed certain"
++ How come? Did you play too fast? Were you low on time? Did you become careless? Go to the root of this loss so as to prevent such things in the future.
"I'd like to win once in awhile" ++ Focus on not losing: avoid mistakes and blunders.

Improving Your Chess - Resources for Beginners and Beyond...
https://www.chess.com/blog/RussBell/improving-your-chess-resources-for-beginners-and-beyond
https://www.chess.com/blog/RussBell
I was never very good. A little background, I just started playing again after about 12 years of not playing at all. I used to be ~1,500 or so. Now? I don't know what happened. I was hovering around 8-900, but then I hit a bad streak. I don't know what is going on, I can't seem to win. I just blew a game where I was really far in the lead and victory seemed certain. What should I do? The problem is, I don't have a lot of time to dedicate to the game. Real life comes first. I don't expect to be amazing, but I'd like to win once in awhile.. what is recommended for improving for someone who has very little time to dedicate to the game? What can I get the most out of?