Know how to safely recover when you get into trouble. Work on your short game.

Agreed here.

Short game is a biggie, especially for us old geezers.

Play with what works. I’ve been playing a lofted driver since 2011 (12-13*). I’ve played some of my best golf with it, 7 wood, 27 hybrid, 7-8-9 irons and 48-56-64 wedges. I just went back to using either a Sumo2 SQ 34H or G10 32. My 8 and 9 iron are 36-40. Vokey 46-10 bent to 44. 48-56-64 with a 58-06K.

My average score is 85. I’ll occasional break 40 for 9 holes.

Buy a good quality eraser.
Keep track of all your shots to see where you need the most improvement, and work on it.

That is a pretty open question without any idea of your typical game, but you cannot go wrong regardless of the number you are trying to break with playing the shot that you know you can make and will not get you in trouble/more trouble (whether fade, draw, short straight shot, ....) and practicing your short game/putting. Breaking 90 is 17 bogeys (no doubles) and one par.

You would need to give some details about your struggles to get any good advice. Without knowing anything about your game all i could say is play to your strengths and use some basic course management. If you don't know if your driver will go right, left or straight then don't use it on the course until you figure it out on the range. A 3-wood, 5-wood or hybrid may be a better choice for you from the tee to put the ball in play. If you hit your 7-iron solid every time then use it as often as you can. If you can't chip use your putter from off the green from just about any distance inside 20 yards. You will probably get closer to the hole in less strokes. A hybrid with a putting stroke is a great choice as well from off the green. Any time there is a hazard or O.B. in play, aim away from it or play a club that will absolutely not reach it. On the range practice making the weakest part of your game stronger and put in lots of time practicing around the green finding at least one shot you can execute well from different lies.

Dependent upon your age and of course you handicap. What tees are you playing? You might consider moving to the next level of tees and have fun, once your game is more comfortable, then move back. Peer pressure to play from the long tees ruins a lot of golfers games and desire to play. Of course you can always go see a PGA professional for assistance.

Not the universal issue solver, but I played with a senior well accomplished golfer many years ago, and he said if I wanted to cut 3-5 strokes off my score to focus on these two things- No two chips, and no three putts. Just focusing on those two things improved my scoring almost immediately. Think about it, you have a chip and try to get cute with it. You leave it short and are forced to chip again. You get that one on and then two putt. In retrospect it would have been better just to get the first chip on the green, two putt and walk off one stroke better then the alternative.

Stop keeping score when you get to 89

stop after 16 holes (LOL).

all kidding aside, the above comments are all quite valid. I'd like to include a few others. but a little more info from you might be helpful. such as (1) are you close to 90 or in the upper 90s? (2) are you always short or long from greens? etc.

1. how often do you practice? at the range, make sure you work on your alignment and work on your directional skills.
2. how is your grip? I found that my grip was VERY weak. After making it stronger, it changed my swing plane, ball flight, etc.
3. the comment on course management is key. play every hole as needing extra stroke - i.e. a Par 3 is a Par 4, etc. Focus on Bogie golf and you'll find it easier to make "par".
3a. if you have say 250 to the pin, rather than try to crush a shot, hit 2 125 yard shots.
4. do you use a quality range finder/GPS? This will provide distances to pins, hazards, etc.
5. this might sound too simple, but DO NOT COUNT YOUR SCORES DURING THE ROUND. If you become too fixated on the "magic number", you'll start pressing too much. Just relax, enjoy the round and the time with friends.
6. if you are working on something in your swing, have 1 swing thought!!!!
7. this should have been #1, but spend some quality time with your PGA professional. They know what to look for and more importantly, how to fix the problems.

If you can focus on many of the comments in this thread, soon you'll be asking how to break 80!!! Keep us posted!

Do you track any statistics? Simple start -
Raw score?
Fairway hit?
# Putts?
Green in regulation - if take 4 shots to get on green on a par 4, record a (+)2.

More than 36 putts? Work on putting. Consider a fitting with a couple lessons. If you 3 putt more than 1-2 holes, breaking 90 will be hard.

Do your double/ triple bogey holes correspond to fairways missed? Or too much dispersion on approach shots and already +2 on getting on green?

An 87 is 15 holes of bogey golf, 2 pars on par 3 holes, and 1 par on a par. 5. Where are you losing shots (and take that to an instructor)?

Everyone wants to go to the range and hit drivers and full swings, there is truth to that. You need to practice full swings for sure. The easiest way to have your score go down is to start close the hole and practice those things. Putting and chipping. If you slowly eliminate 3 putts on greens your score will go down, at the some time if you get your chip shots closer to the hole the putting will be easier etc etc. I recommend practicing short game.