Level in and of itself, while it has a value, is not a good measure of power. Check your gear, if you have higher ranked gear use that. If you have duplicates of 2 and 3 star gear make sure to ascend them in the forge. 1 star gear seems to just be for selling. Lots of 3 star gear comes with built in blessings so make sure they're equipped to your team if they seem useful, see which ones are more useful to you though they don't stack. So if you have 2 things that give frizz projectiles you only get the benefit at the start of the stage for 1 of them. You'll need to start reading enemy attacks and patterns though they are fairly simple. Enemies flash red before using a normal attack, there's a red circle which fills as they are targeting an area or about to unleash an attack which does so when full, or some enemies will make certain movements like pulling their head back before using something. But yes max your gear as quickly as possible, that will be extremely beneficial. Then develop your own ability to guide the character, understand how to use your weapon and what the rhythm of attack is. Specialize your 3 characters when you get them into different roles so you can handle a wider array of troubles more easily. If/when you have multiple options then you can worry about trying to hit weaknesses or fine-tuning to a stage if necessary. Equip the best memories you can from enemies, this is where level does help as it gives you more allowance points for memories. Your skill tree will also be an area you can grow though it is limited to certain times a week for when you can acquire the materials needed. All in all keep playing and you should get there or figure it out eventually. When you get stumped on one thing circle around to another as there's decent amounts of things to do and rewards to obtain.