Ok, first i wanna start by saying this is how i've been successful in the past and ofc is my own opinion.

As for tips for starting out, pool everything, dont let urself be baited by the new server event rankings. The best you can do, is hold everything for their respective event, refines, first week of each month, cave keys, last week, etc.... This way u get the most out of everything and through a month, u'll have gotten max value out of it and your power should reflect. Also, dont waste your coupons, spend them during events on power, not in the shop. First early game, the only real exception to buying power only is iruka, he's a good ninja that will * with u for a long long time, and will always be ur to-go ninja for ninetails event. As for daily goals, try to maximize ur exp as its importent to get to 53 reither fast, at this point u have summons and summon cultivations unlocked, alot of power from this. Another thing is to ensure u've done every event you can each day, this includes daily practice, max ninja exams, daily events during the evening and more. This last point is even more importent now with the sun and moon scroll system, as u get them from participating, and again, u spend these on alot of good power items. If you're unsure on what to spend, you can get good discounts on spesific items in treasure of the sage event, but if u need little of everything, hold your coupons for lucky board, always good power to be gotten from this.

As for early game power that cant be found on inspection and makes a difference could be: Ninja stars, some ninja having higher stats(growth rates) than others and therefor giving more sheet power, if you've reached the point of summons, runes dont show, neither do cultivations. Also, might just be that someone forgot ninja cultivations or have lower strengthens on gear. Group skills have alot to say, spesially early on. And maybe more so than anything else, ninja tools from team instances, what u get is random, so someone who got one of each instead only dupes, will have more power than the other. Cant really thing of anything else early game.

I hope this helps you out, and if u got any questions, feel free to PM me, ill respond when i see it =)