My Fiance has a man cave and it's more of a junk yard .

Does his space have a door that you can close? If so, let it be. If not offer to help tidy the area up. Show him photos of well organized spaces and do the project together.

My hubby's man cave looked like a junkyard. I helped him patch holes with dab, paint and organize. I let him decorate using what he already had. Used old wooden drawers all painted the same color to hold cables and other items. He is so proud of how good it looks and how organized it is that he keeps it clean and picked up. But the secret was to let him see how much easier it is when you know where everything is and everything has a place.

Love him.... love his man cave.... or what ever it is.... Any time I go in my husbands gun room... it is only to open the safe (I am faster at the combination than he is)... he doesn't want to organize it.. or let me in there to do it...so HE gets to vacuum it and clean it.

It's his room. Stay out.

Personally, I have never found anything that works, it's his man cave. I just learned to let him have his mess, and make sure no guests go in there. I tried organizing but it's not his way of operating.

The whole genesis of the man-cave was for guys to have a space to call their own, after all most homes with all its rooms are decorate, designed and managed by women. Respect his corner of the World, you can offer, but back off if he's not receptive.

If you let him have his space as he likes then when it comes to a space for yourself he will won't be saying what you should be doing ;)

Even if it is "his" space there is no reason it can't be kept neat and clean. Get him in a habit of simply throwing all trash away every morning and picking stuff up and putting it away. My hubby knows that if he does that I won't go in his "man cave". But if he doesn't that gives me permission to do it for him. And when I clean I show no mercy so he is better off doing it himself. Organize stuff in plastic containers or crates. One crate for cables, etc.

Bins (pretty ones), perhaps labeled, on a bookcase seems like it would help your cause.