There are indeed many traps for spenders. If you see something like "BUY NOW" its a good sign that you probably dont need to buy it.
If you want a serious approach, you can calculate which feature will give you the most power. For example, rushing armor isn't a good option imo, since you will be getting a lot of cloths anyway and can spend moon scrolls on something else.
A definitely useful tip is to not spend your essenses from ultimate training on weak ninja tools. Wait until you get max ones. Also check topics about powerup features by ICE, very useful:
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