There are a few general things any player needs to do if they haven?t already done so, as well as a general guide focused on people transitioning into the mid-game.
1: FARM THE MAIN SUPPORT MONSTERS.
Generally the 3 main support monsters are Ahman (Light Bearman), Shannon (Wind Pixie), and Bernard (Wind Griffon). These 3 units make a wonderful addition to any ToA/Cairos Dungeon team. Other good units to farm would be Belladon (Light Inugami), Darion (Light Vagabond), Konamiya (Water Garuda), and Neal (Light Fairy). These all can be good additions as well, but are more situational. To my knowledge these are all farmable, or extremely easy to get access to via shop.
EDIT: I would like to add a monster to this, although he?s not a support. Ramagos is an amazing addition to any team, and WILL carry you to late game. Sadly he falls off a little bit there, but comes back unbelievably strong once you hit the higher ranks of Arena. Overall, he?s a great monster and I regret not leveling him up when I was newer to the game.
2: DO NOT NEGLECT FARMING FOR RUNES.
You could have a badass team of 6* natural 5* monsters, but they could be rendered useless if they don?t have greater than 3* runes. You HAVE to spend time farming for good runes for your units. A good milestone to hit is B6 Giants, because you can get a good inflow of decent runes, with a very rare chance of getting a 6* rune. It is also decent mana to farm there as well. Going any higher into the Giant?s Keep can be much harder, and Dragon?s Lair is on a tier of its own. And although the main stat difference between 3-5* isn?t too far off, the sub-stats can differ greatly.
3: FULLY UNLOCK ALL OF THE SLOTS IN YOUR SHOP.
When you hit level 28 (if I am correct), 6* runes will begin to show up in your shop. If you are unable to clear higher levels of Giant?s Keep or Dragon?s Lair, this could be your sole inflow of high level runes. Although 6* runes can be rare, you can find other really good runes in the Shop as well. I would recommend keeping at LEAST 400k mana stones at all times, as you can buy the majority of good runes. You will also get a decent amount of Mystical Scrolls, if you are on a lot it could even be 1-2 a day. This may not seem like much, but it really does add up.
4: ALWAYS DO YOUR ?DAILIES?.
Doing a daily would be obviously clearing all of the daily missions, but also doing things like clearing the Rivals in Arena as well. If you want to keep a good overall balance, do a run of Hall of Magic, the Elemental Dungeon of the day, Giant?s Keep, Dragon?s Lair, and maybe do a secret dungeon. At the very least, this will allow you to gauge your teams progress, and when you finally are able to clear something higher, you?ll know you are doing something right:). If you do these things daily, your crystals will add up, as well as spare essences and runes you will acquire from the Giant/Dragon.
5: DON?T BE AN IDIOT LIKE ME, AND WASTE YOUR CRYSTALS RIGHT WHEN YOU GET THEM.
Even at level 40, this is something I struggle with. Try to always save your crystals to at least 225, to get a Summoner Pack, or to 750, to get a Premium Pack. Although this doesn?t influence your luck at all, it is just more beneficial to you in the long run. Also NEVER spend crystals on refreshing the Temple of Wishes, the chances of you actually getting something good is extremely unlikely. Another good use of crystals would be to save up to 200-400 crystals and buy a 1 or 3 day EXP booster, then spending some time at somewhere like faimon and refreshing your energy to powerlevel some monsters. This can give you a nice boost if you are struggling in Cairos or ToA, and you should be doing this every now and then.
6: ALWAYS USE YOUR ARENA INVITATIONS.
Although you may lose, at least get the glory points for participating. Glory points are very, very useful, because getting a weekly Devilmon is important to leveling up the skills on rare monsters, as well as unlocking Glory buildings. Your best use of glory points is something like this order. Devilmon ?> Mysterious Plant ?> Sanctum of Energy ?> Sky Tribute Totem ?> Any other Glory buildings you might want to invest in ?> Mystical Scroll/Elemental Scrolls. If you are low on energy, this could be a good place to get 5 or so from the battles, and then 10 from the Daily Mission.
7: ACHIEVEMENTS/MISSIONS CAN HAVE SOME REALLY NICE REWARDS.
If you have to spend a few crystals to get to one, like reviving 1-3 times on B7 of a Elemental Dungeon to get the Mystical scroll, do it. I haven?t done the Achievements/Missions in a while, because I have completed almost all of them (Darn you monster wish!), but I think you have the judgment to know which ones to shoot for.
8: KEEP IN MIND THAT THIS IS A GRINDING AND PATIENCE GAME.
In this game it may take a very long time to accomplish your goals, but that can make it vastly better when you achieve them. Between farming for runes, mana, essenses, monsters, xp, scenarios, ToA, dungeons, and doing arena, there is a nearly unlimited amount of things you can do. But keep at it, and you WILL get things done!
9: AND FINALLY, DON?T BE AFRAID TO ASK FOR HELP!
The reddit community as well as the SWSA community is generally pretty helpful, and we all have good advice to give. Before you do anything major, try to get input from someone else, so you don?t make some of the same mistakes we did when we first started playing. For example, I fed my Water PT very early in the game, before I knew how good he was.
Please leave a comment if there are any mistakes in here, or if there is anything I missed. I really hope this helps, best of luck!