Adding onto s1volu. Save your seal scrolls and spend it after you have access to GNW treasure and only when there is a seal scroll rebate - it happens at least once a month so pay attention to the forums.

Focus on awakening your ninjas (at least 12 for ranked) and max upgrading your equipment before deciding continue with plot instances. Be patient as this cannot be stressed enough or you will become food for players who know better or has money. There's more things you can do to avoid this but I'm not sure if you are aware of it.