Frustated and Not To Be Panicked

Assalamualaikum wbt, 
The main objective of this post was to throw every negative things I encounter but I realize that wont do any good so lets take it on the bright side.
Every solution have their own problem right? (yes, you read it correctly), so this gonna be an advice for myself and maybe to those who kind of gonna experience it on the future. 
The story is, I have this photo shoot job that required me to spend two hours on side, so I tot that one full charged battery equipped on my Sony A6000 will be enough. Apparently not! The hours on the event dragged longer than I expected and my battery on the first hour is on its critical situation, thank God all the important shoot already covered, the things that left is ‘the clown show’. 
So these are few advice for an armature-solo photographer like me. Panic is the last thing I wanna do. 

1. Before jumping into a side, make sure your gear on 100% ready. Battery fully charged, make sure your extra lens, extra battery already in the bag, your memory card emptied or at least enough for all the pictures you gonna take. Today I decided to take photo in RAW format, therefore I forgot the facts that using a 16gb memory card will not covers the entire events. *facepalm* Hence, I need to manually deleted some of overexposed photos to cover the whole event – the least I can do. 
2. Know the event tentative. When you’re in a situation who dont know anything, somehow you put yourselves in a pretty risky situation. Like me, I know basically on typical birthday celebration, you’ll have doorgift, cakes, presents, lots of children, lots of food. Other thing I do not know is when they hired buskers, and clown shows session. So its really put me in a less luck situation where I just covered maybe 30% of busking and clowning sessions. – at least I manage to cover it right? (lols) 
3. Most important thing, is do not get panicked, to tell your customer your camera battery is about to die is probably a bad decision – but I choose to let my client know, how unready I am, and pray for them to understand. And they choose not to take it seriously which also means ‘as long as you’ve covered the main features’ – but I do take it seriously, is my own mistake that I forget to charge the other one battery. 
4, Regret, after all the experience I encounter, I feel really regret now and I need to determine myself to not to commit the same mistakes again. Since my Sony A6000 have in body charging, my next goal is gonna buy external battery charger. Cause using Sony A6000 with live view gonna make it drain battery fast, Sigh –‘
Thats all for now, Hopefully whenever I encounter this post again I’ll already getting back stronger, and less mistakes. Thank you to my client for having me, I’m always looking forward to serve my customer better. Honestly, I’m very enjoyed today sessions. ^^