I've learned you have to do several things every day to slowly progress in this game. Do these 5 things every day and you'll push through the game a little more every day.
1) Log in!
I can't stress this enough. Logging in daily is the fastest way to get great minimon and other stuff for free. Like I mentioned earlier, on day 7 I got a 5 star Noen! After the initial 7-day attendance, it becomes a 28 day long attendance calendar that every 7th day you get another 4-5 star summon. The last day is a 6 star summon I believe
2) Run the daily dungeon (duh).
You can run the daily dungeon once a day and it gives super critical evolution stones. These stones are used in fixed evolutions. What is a fixed evolution? It's an evolution where you keep the minimon you're trying to evolve. You can read more about different evolution types in my other posts.
Also, hold on to your 1 star and 2 star evolution stones. You'll want to combine them into 3 star evolution stone later on, so you can evolve good 3 star minimon, like biyo, into their 4 star versions (which are generally much stronger, or heroes).
3) Level, upgrade and equip your minimon.
Leveling your minimon not only makes your team stronger, but you can combine max level and max upgrade minimon of the same grade to make a random minimon of a higher star level. Though you may have already known that. What's not obvious is that certain minimon and heroes are much better suited to complete certain levels, than others. If your stuck on a level in hard mode, try leveling an alternate hero whose attribute is super effective in that level. Chances are it'll be more successful than your "best mon". Strength in diversity!
Also, if you've got your eye on a minimon you think is invaluable in your team, *cough* ARIEL, equip that bad boy! But, when I random evolve my minimon it's going to lose that equipment! Nayyy, don't random evolve minimon that you want in your team. Even if they're just 3 star, eventually you're going to get those phat stones to evolve them. And from experience, it's worth the wait... RIP Ariel.
4) Push as far as you can through the campaign.
Getting as far as possible in the campaign is critical. This is because the farther along you get the higher grade minimon that you acquire. This means the time it takes to get a 4 star evolution is drastically shorter when you're getting 3 star mons versus evolving a bunch of 1 star mons.
Pushing though the campaign also strengthens your team. As you team level increases, you can do higher level daily dungeon and get higher level stones. This makes evolution even faster! See what I'm getting at?
Get as far as possible, when you hit a wall, farm the level before it for mons. That's progression baby!
5) Use up all your energy and scales.
Super important to use up all your energy and scales every day to make sure you don't cap your energy and scale generation. This can be tough in this game since you're constantly being sent scales and energy. But the games saving grace is it's expanded auto play functionality. Slap that game on auto repitition, with auto skill and go take a shower for once! Kidding, you don't actually have to shower, but please do spend all your resources while you sleep.
Why is this so important though? Well, keeping you energy generation up is necessary so you can run more dungeons and other stuff as well. And trust me, you're going to need to run LOTS of dungeons and stuff in this game. Not just to collect minimon and equipment, but to collect coins! Everything gets pretty expensive, pretty fast.