There are various solution to neck dive.
I'm afraid my solution doesn't look very cool, but it works for me - fasten the strap at the headstock, rather than the neck heel or top horn.
I find that especially comfortable with a nice wide strap; sometimes a wide strap on its own helps, but it's the headstock anchoring that really allows it to hang stably and free up my fretting hand for fretting instead of holding the instrument up.
Bass guitar forums are a good place to search for solutions for neck dive, as it's a common problem with bass.
music.stackexchange.com/users/18896/topo Reinstate Monica
When seated, the guitar will be either on your left or right thigh - most seem to favour right, although the accepted for classical is left.
When you stand up, the centre of gravity changes, mainly due to where the strap buttons support the guitar.
The lower the guitar is slung, the more exaggerated the problem is.
A strap that doesn't slide round is probably the only answer.
music.stackexchange.com/users/2808/Tim
This is an issue on bass also - you could try lighter tuners, there is a surprising amount of weight in six of those.
Try and find ones where the screw holes are in the same places to avoid excessive damage.
Also consider a more grippy strap that will shift around less so you can place your guitar where you want and balance will not be an issue.
music.stackexchange.com/users/36503/bigbadmouse
Hollow bodies naturally have lighter bodies, so they are more prone to neck dive.
Short scale basses also suffer from this issue.
Get yourself a long, wide, soft strap
(Ernie Ball makes a good one) that you can adjust well.
Lengthen the strap, pulling the ax downwards and neck upwards, wedging it with the strap around your shoulder and back.
Keep experimenting until you find the right angle for you - take your time until you find the right point of balance.
Eventually you will find it.
Sometimes you will have to raise the headstock quite a bit to get into a comfortable playing position, depending on your style of play.
You can also try putting something heavy down by the bottom of the guitar to pull the neck back up.
Here's a good thread from TalkBass.com about it the problem: Short scale, hollow/semi-hollow with no neck dive?
I picked up a cheap Rogue VB100 violin bass and like the sound (with some setup work and flats) - but it has terminal neck dive (as I expected).
I "solved" the problem by putting 8 oz of fishing sinkers in a Neotech wireless pouch on the strap - not a very elegant solution...
Lots more there.
music.stackexchange.com/users/10902/Stinkfoot
You could experiment with different straps.
Some straps are elastic, to mitigate the weight of heavier guitars (Les Paul, basses).
My guess is such a strap might allow you to balance the weight of the guitar better when standing.
Even better, I have a leather strap that is suede on the inside.
It really doesn't slide over my shoulders.
It is kind of annoying, if I adjust the angle of the guitar, it makes my shirt bunch up!
But I imagine it could help with neck dive as well.
music.stackexchange.com/users/48473/scott
Pick up your guitar, strap up, and stand up with it.
Take the strap off of the peg on the bottom of your guitars body and hold it there.
Let go of your neck.
Most likely the body dove toward the floor, since most likely it's much heavier than the neck.
Grab the neck again and put it in a comfortable playing position.
While balancing the guitar, move the strap button up toward your low E string.
Eventually you'll find the spot where it balances correctly.
Mark it with a pencil and drill a hole there for a new strap button.
Move strap button to new spot; no more dives.
music.stackexchange.com/users/44188/Tama
I have an arch-top Epiphone that I really like the feel of the neck when I'm playing seated, but when I stand and play, the weight of the headstock and neck keep making a dive for the floor and I spend a lot of time and energy just trying to keep it propped up in a comfortable playing position. Any one have a workable solution for me?
How to deal with a guitar balance problem?
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music.stackexchange.com/users/44636/skinny peacock
When you play an Am fingering with a capo on the 4th fret, the sounding chord is C#m and  sound is what counts. When other people listen to your guitar and sing or play along with it, they don't need to know how you used a capo. The capo thing can get real confusing and all the capo cheat sheets online look different, so its hard to know what's the best logic to use to figure this stuff out. The best logic to understand how it functions is to learn the chromatic scale  to learn the names of the strings and  to understand what tones will sound when you play a certain chord pattern    You could experiment with different straps and you eventually you'll find the spot where it balances correctly.
Fasten the strap around the neck rather than at the headstock. I prefer to use a wide strap instead of a for these, because it holds the instrument well and frees up my hand. When you're seated, the guitar will be on your left or right - the majority of guitarists prefer to sit on their left, but it's normally seated to the thigh. Tightening a strap is the only way to make it more comfortable. Straps are made from elastomerized materials to help reduce the weight of heavier instruments. You could experiment with different straps. Drill a hole and mark the new strap there with a pencil to mount a new button. It will balance when the weight is in the center of the scale.