Your most immediate goal is to clear the main story quests! As highlighted in the image, you can get first clear reward DigiRubies. These Rubies are necessary for you to summon other Digimon! You can also get completion bonuses by clearing the objectives for 3-star mission clears. The Rubies aren’t the only draw – no pun intended – of the main stories. You’ll also be unlocking various features of the game as you progress.
Basically, clearing the main story is important!
Where applicable, do keep an eye out for “step-up summons”! This goes double if they provide bonus items or guaranteed summons, like the WarGreymon summon. If you’re rerolling, you would prefer to get Digimon which can Digivolve up till Mega forms. In general, Megas will have more stats and are more powerful than Ultimates. It’s important to decide how to distribute your resources as Digimon will not grow stronger unless you give them bits or use work-out items on them.
Unfortunately, your starter Digimon, Herissmon, isn’t just very good. You can leave him to upgrade another time if you have the resources.
You’ll likely be gated by your energy as you try to go through the main story quests. Energy will be refreshed whenever you level, for one thing. You can also obtain energy drinks that will refill up to your current max energy. Joining a DigiGuild is especially important as supporting your fellow DigiGuild members can provide you energy DIRECTLY! They will also provide social points that you can exchange for various items. Join one as soon as you are able!
Doing Challenges, Missions, and Quests are good for you too. Not only will you get various resources, Daily Quests also provide a steady stream of DigiRubies. Do not miss out on Daily Quests!
For Dimensional Vortex quests, the more energy you spend, the better the drops. These you can somewhat put aside until your Digimon reach a roadblock of sorts where you cannot Awaken them. Do try the Bit Vortex Quest at least. You will need a lot of it to upgrade your Digimon! If you have nothing else to do, then work on spamming Clash Battles (raids). These take no energy, and will give Digivolving material.
Take advantage of the login bonuses, especially seasonal ones. Halloween bonuses have gone live, so get in there and begin your Digimon adventure.