Just started today

For now, save your Blue Crystals and try not to use your Eligma unless absolutely necessary.

Just push through the regions and collect your Stellar Jade while watching the story.

Push your missions as far as possible to raise your cafe rank. Just participating in Total Assault/Decisive Battles gives you basic rewards, so make sure to claim them. Don't do pointless gacha pulls, or you'll be looking to quit.

Pushing through regions is important, but if you get stuck in the middle, take a break by watching the story, then leisurely clear out enemies and proceed with the missions. The gacha here is brutal, so definitely save your Blue Caches. You need a plan before going into this gacha.