I personally recommend you using your coupons/ingots into events. Using it on power and some ninjas you know will stay with you for mid to end-game would be best.
There are actually quite a few good recharge/spending events that are going on right now. I would recommend taking advantage of the Treasure of the Sage event and using your coupons/ingots on things like refinement runes or ninjas including Sakura at a discount, Naruto at a discount, and Iruka at a discount. There are lots to choose from ninja wise!
A wise person once told me to invest in power first over ninja because power stays with you forever, while some ninjas falls off. Which means, investing to buy the various packs in the Konoha Gift Shop such as the Cave Key Gift Pack, level 6 magatamas, and charm materials pack. There is also a Cave Key Gift Pack available in the Mystery Fruits event!
Hope that helps!
~Jib
P.S. Try to focus on the more current ninjas over the older ones. Many of the older ninjas have become harder to stay relevant in the current meta. Go for the staple picks or even Kage treasure ninjas, I wouldn't pool your resources into something like Orochimaru unless its a ninja you want to add to your collection=p If you don't know what to choose, choose power, it is the best way to make use of coupons/ingots!
Best thing is, many of the events stack, so if you can plan what you need and what you want to use, you can make the most of your coupons/ingots => This post was last edited by Jiburiru at 2017-5-20 01:03