I suggest that you find a guild to join if you are not already in one as they can help you with a lot of things including resources to help you move up the levels, best thing I ever did was join a guild as I would not have stayed with the the game. Find a good battle sim and use it to redo all your battle guides and don't forget to review as you acquire more gens and access to new troops.
In the lower levels it is a slow grind as you build your capabilities so slow and steady is the best approach, after all you are learning how the game works.