To simplify things: Tinnitus is a mind game. It often begins in the ear, but it is maintained by the brain–sometimes even in the absence of what set it off at the ear level in the first place. The more you pay attention to it, the louder it will get over time. The better you get at ignoring it, the softer it will get. If the tinnitus is perceived as some sort of warning signal (e.g. "oh no, it’s a tumor!) it will get louder over time because the brain is very interested in things that are novel, important, or dangerous. If the tinnitus is perceived as neutral or unimportant, the brain will slowly fade it into the background as it does the hum of your fridge or the feeling of your clothing. The tinnitus will probably always be with you, and will be there if you stop and listen hard for it, or will be there if your body is under more stress that usual (you’re sick, you’re tired, you’re hungover, etc.), but the better you get at ignoring and not worrying over it the softer it will get over time and the longer the periods will be when you don’t notice it. You have some level of cognitive control over this, but at the times when it is particularly bothersome I’d recommend throwing on some music and masking it out and then engaging in whatever stress-lowering thing you do to avoid strengthening those bad-tinnitus-stress-time neural connections.
This isn’t a satisfying answer and it is a slow solution, but it is the best answer at this time. Apart from certain pre-existing deficiencies, which have been mentioned, there is no magic pill. Apart from Meneire’s, there’s is no evidence that salt has any effect on tinnitus (and evidence of the effectiveness of low-salt diets for Meniere’s patients is pretty limited). Don’t worry about caffeine or alcohol–if you are in withdrawal from caffeine of if you are hung-over the tinnitus will probably get worse, but only because your body is under more stress than normal and the tinnitus will go back down as you recover. There are lots and lots of internet scams trying to take your money for the promise of some sort of instant cure, ignore them all.
Live your life, distract yourself from your tinnitus, spend as little time thinking about it as possible, and it will calm down over time. It you tend to be an anxious person or have issues with depression, you might need extra help to do this.