How well prepared do you feel for your next gig? Sure, you've practiced, memorised the lyrics, got the stems and hardware all synced... but there's other things to consider as G.W. Childs explains.
Not necesarily the "essentials" but definitely necesary gig bag items!
1. Spare Phone Charging Cable
Whether you use Android, or an iPhone, you really should contemplate keeping a spare charging cable around in the old backpack. This is doubly true if you are making music off of your iPad. Performers, when on tour, or just playing a one-off show in your hometown tend to go through a lot of phone calls, coordinating, getting the guest list ready and keeping the social media feed updated with pics of the show, and any special promotion to get more people to come. Don’t forget your charge cord, and cut yourself off!
A spare charging cable is always handy!
2. Sugru
One substance that I always keep with me, these days, is Sugru. Being part silly putty, and part bonding compound, Sugru is great for making quick, makeshift stands, for tabletop devices, splicing cables, splicing headphones, making cord holders, fixing glasses and loads of other practical applications. And, it comes in a ton of colors. I’ve even used it to fix my car before! If you’re a musician, performer, artist, or interpretive dancer that sometimes finds yourself in strange situations where things break, and you need a quick fix, keep some of this stuff around! 
Sugru: the next best thing since duct tape!
3. Tackle Box
I know a few very organized musicians that keep a small, segmented tackle box, similar to the kind used for fishing, in their backpack. These also happen to be the guys that everyone runs to, when something goes down! Strangely coincidental, right?  It sounds a little overly nerdy. But, when you pull out a tackle box and see all of your adapters in one spot, cables in another, and things are easy to pick apart, you find yourself getting things up and running faster, and just much more... organized.  
A tackle box will save you headaches!
4. Extra Earbuds, or Headphones 
Personally, I always keep a pair of earbuds around, as they are easy to carry, and you never know when you’ll need to plug-in direct to an output, or mixer, or piece of gear to check the line, hear specific audio problems, like feedback, or you just want to chill in the VIP room, and listen to some tunes, before the show. Always keep headphones, or earbuds. I like earbuds, as they are easily stashed, and can even fit in extra small pockets in my jeans. However, there’s always a spare in the backpack. I can’t live without them!
Earbuds: don't leave home without them!
5. Extra Universal Adapter
These devices are especially cheap, when shopping at places like Walmart, and boy can they save you, when you accidentally forgot a mission critical wall wart. Universal power adapters run around 12–14 dollars, and can be switched to match the electrical demands of most, modern music gear. I’ve used a universal adapter with my MIDI patchbay, volca devices, and even video games. Remember: A missing power supply for certain, critical pieces of gear, can completely cancel a show. Be prepared!
A few bucks well spent!
6. Back Up For Back Up
If you’re playing a lot of shows, you might consider keeping a copy of your set on your phone, and in addition, on a CD. You never know when equipment disaster, or theft could strike, and this will leave you without a show. Sure, having an audio copy of the set isn’t as desirable for all musicians involved. But, at least you still keep your momentum, and you still get paid! Although, I would suggest, if there are vocals in your set, keep the back up without vocals. Canned backup music is one thing, but nobody wants to hear someone lip-sync.
7. Cable Ties
The spaghetti effect is real, especially if you’re running primarily hardware. Keep your stage safe, and the rest of your life, by tying those cables down. For one thing, it looks pretty, but it also keeps you from having to constantly fear tripping over something, or knocking something over, either on stage, or in the studio. However, if you do start rocking cable ties, you might also consider carrying...
8. Tools!
Pliers, with a built-in set of wire cutters are always handy. You never know when you might need to modify a piece of gear, on the go. Or, cut a cable tie! Actually, the ideal situation is a small toolkit, that is compact enough to fit in your gig bag, and sports pliers, screwdrivers, wire cutters and more. Having access to tools on the go is also extremely helpful for computer upgrades while on tour, and the additional satisfaction of feeling like MacGyver!
You never know when you're going to need a screwdriver!
9. Extra Shirt!
If you’ve got one of those giant commando backpacks, you might think of keeping a clean shirt, nearby, as to avoid smelling a little pungent, by the time the show starts. In addition, keeping a little bit of mouthwash, or some breath mints are never a bad idea, along with some deodorant. After all, shows are a great place to meet people for romantic purposes, also! Tip: When it comes to close, you might consider placing a shirt in a gallon size Ziploc, along with other items that need to stay dry. You never know when you might get rained on, or you might have some guy spill a beer on your bag, while trying to hit on your groupie.
Keep your spare t-shirt dry.
10. Small Snacks!
Keeping a little food on the go can only help. Seriously! Food keeps you powered, and keeps your blood sugar up. Something you don’t want to drop during a sound check with a frustrating sound guy. By keeping yourself fed, even with light snacks, you ensure that you’re always working at optimum performance. And, you’ll keep your metabolism up, too! Sure, venues will sometimes make food allowances for performers, if you’re playing a show. But, you may wait for a long time, before you actually get fed. Plus, by keeping an extra Granola bar, handy, you may also quell the hungry of an angry bandmate, acting out! Just make sure you keep it small, compact, sealed, and ready available.
As a former military man, military photographer, soldier, and cable dog, I can tell you need to be on top of your gear. Knowing where things are, knowing what you have, means being prepared, and being pro. This is not an area where you can be too organized. If you need to label, do it, buy that label gun. Whatever you do, keep an active inventory. It only requires that you just have a look, once a week, and see what’s missing. And, if you ever notice yourself missing something consistently, add it to your check list! 
Original Source: Here