It depends on what power range you are currently at… Since you are also asking about leveling up, I’ll assume that you are on a relatively new server.

It is pretty simple. Do all your dailies. Participate in all events. Do plunder and don’t rush leveling.

Make sure to do the highest Ti for your power as Ti gives a nice power boost.

Try to go as far in ninja exam as possible. Higher exam levels = more magatma and scrolls.

Aside from that, most power comes from where you spend your coupons, so spend them wisely.

First, I recommend you to stock up power items for rebates, especially charm, and refine rebates. You don’t need to max out the rebate though. Here is a post for the rebates and best deals https://forum-narutoen.oasgames.com/page/show-post-31402-1.html

Charms you can get from the ultimate training. If they are not enough then the lucky board is your best friend until you are about 50-60k bp. Get med refines from the monthly events, group shop, and the weekly events. I don’t recommend spending coupons on med refines, since you can get them for free.

Make those rebates a priority. When you find that you have enough power items for the rebates, you can spend your coupons if there is a good event. If there is no good event, save them. Always come to the strategy section on Thursdays or Fridays and find event guides. Those will help you know which items are worth redeeming from the different events.

Outfits will also help boost your power. Redeem fragments from events and only finish them up with coupons. You can buy Anbu outfit from konoha outlet though, as this outfit is really good and you won’t find it in redeeming events anymore.

Lastly, and here is something that a lot of F2P seem to ignore:

Do Not Spend On RNG Wheels For Ninja!

Always Pick Power Over Ninja! As a F2P you will only be able to buy 1 or 2 event ninja, so think wisely about which ninja you want to use and collect their fragments slowly.