Take a look at any number of aids on video thru Youtube. Get the gist of them, then you can usually create any one of them for pennies out of dish towels, old shafts, and a bungee cord. The way to get better is to play. This has been discussed by all the "pundits" in the last few years- All the players these days look exactly alike for the most part. You REALLY can't tell the players without a scorecard. You KNEW Nicklaus' swing, Trevino was impossible to miss, Palmer's slash could be seen from across several fairways. They teach the exact same swing these days when the most important part of the swing lasts less than 1/30th of a second- the time the ball is actually touching the clubface. How you get it there is unimportant. Basics of the swing, alignment, etc... can be learned through instruction and repetition. What would happen if Jim Furyk was just starting to play college golf now? They'd tell him to go home and learn a different game. Since almost a third of the game is putting, buy a matt and putt... putt, and putt some more.
Since you've played before, I would guess you have the basics down- it's consistency and accuracy that bedevils everyone. You probably have a swing that you've used and can play with that. Don't CHANGE anything dramatically, just keep working with the basics adjusting for YOUR swing.
I was getting sloppy playing with guys who weren't going to beat me even if I took dbl's on the last 9 holes. It didn't matter. I decided to take it upon myself to beat them to a pulp instead of just slogging along. It might give them incentive to try and get better and make things more interesting. I started going to the range and almost starting from scratch but working with MY swing. I've played for about 40 years now and I wasn't going to radically alter my ingrained muscle memory. Worked on my stance first, then moved onto a bit more hip rotation, weight shift, then adjusted swing plane, make sure I see the clubhead strike the ball (in other words- keeping my head 'down'), etc... some worked better than others. I kept what worked and moved on. Since I started over the winter, I've picked up 20 yds on the drive (some of that might be equipment- new R11s), improved accuracy with the irons, resulting in about 4-5 strokes better than last year so far. It's only been a month or so since I put the Super Stroke oversize grip on the putter, but that made an improvement in putting, especially in that range from 3-8 feet. Last 3 rounds, no 3 putts.
Nothing radical, no "devices" or aids, other than stretching and warming up with that Torc swing weight before practicing or playing. And nothing more than going back to basics of balance, tempo and the desire to improve. I find that once in awhile, I regress and feel myself sliding into old habits on a few holes. I just stand off to the side on the tee and try and "re-groove". If it doesn't work, I don't force it. I'll play with what I got and work on it some more at the range the next time.
So hit the range and work on your ball striking and the like, but don't fiddle around while on the course. The course is for playing, the range is for practice. Don't let anyone ELSE tell you "you might want to try...." or "turn your hands", etc... while your playing with them. You want as little to think about when you're playing, otherwise you'll tense up and play like poop.