For a new player, the best advice I can give you is to save your coupons and seal scrolls. Aim for at least 20k coupons to be spent in a fukurokumaru deal alongside good events. By doing so, you can get way more value for what you spend. As for a good ninja to spend on, sage of six paths naruto or konan angel of god are always good choices. As for seal scrolls, aim to save up at least 300 seals and then spend it all on recruitment feedback event.