Few random tips for people
1) Upgrading skills is VERY impactful but ranges greatly character to character. Make sure you look at the hero records to see what a max level character for each star has for stats and skill scaling
2) Watch for the map changes to see where 1/2 stam goes, multiple ones on hard and normal can exist but they tend to be first few maps (fuck you!). ANYTIME you see 1/2 stam that drops hero pieces of a key person for you OR 6 star that you have and may evolve these need to be priority over everything as far as stamina usage goes. They are only on useful places ever so ofton so make sure to spam them until you get lvl 10-15 at least on skills. Makes a big difference when skills are doing 50-100% more damage particular on spamming gods. Key ones that are common are Jeane (GET THIS, 11 sec invuln = amazing), Leo (useful, at least get lvl 10-15), Richard (same). Those are the common 3, rest are low tier folks that are fairly common in your travels. Also if you see a Robin 1/2 stam fucking bust that bitch out, burn a gem or two. I didn't realize it the first time I saw and have hardly ever seen since. Robin is arguably the best archer (depending on how you use him) and usually a double attack stacking archer since his attack speed is solid so you will have maximum attack potential thus scaling his fairly fast refreshing ability is a TOP priority
3) Guild quests; get in one. You can mass spam a few of the quests that most people don't take advantage of and get a lot of guild points to train leadership skills. Leadership skills make a HUGE difference so you need a few key ones maxed asap. If you get a few q-passes save them for when a guild quest says special dungeon X _. Just spam you q-passes and burn a few gems if you don't have 2-3 max LS's to use in certain situations, its the best use of your gems I assure you. Also if its take a guild friend to a fight, you want to go the single boss round of the lowest stamina map and spam it. The only exception is if you have a 1/2 stam map further out. This works perfect for Jeana, I had her skill to 20 at 3 stam a map with like <30 second fights and got mass guild contributions & pieces for her skills
4) Critical leadership skills; depends on who you have but core ones you want to focus are Richard for 60% attack (water), Robin for 60% attack (earth), Tristan for 60% attack across the board, and Minerva (40% attack & HP but does not apply to her). These are huge and completely change fights. Minevera almost always should be your go to in pvp unless you need Morgana for immunity from Venus charms. I can beat mid tier Venus's that don't have 100% chains (you need skill 17 for infinitive loop) because my Minerva gives me a lot of sustainability and packs a punch with the buff.
5) Pillaging; take advantage of the above leadership skills. Elemental advantage damage plus a 60% attack leader blows people up hard core. Even if your hero is less quality, if you see a team who has 2 red tanks and a 3rd red dps, load up a less effective blue team and you have a huge advantage especially if you have Richard at 60% etc. Also if you are at all serious about the game and keep an eye on it, don't be afraid to spend your gold searching for good opponents. The gems per day for finishing in top ___ is nice particularly for F2P since you pretty have equal shot at them. Just remember, getting a sweet 200 soul stone win is the same as having to win 20 10 stone wins; we are playing with a finite amount of pillages you can do in a day and gold itself is about useless at this point since card packs are so shit so spend the gold to find a good opponent. My rule of thumb is I never go under a 20 stone opponent and I keep searching for 100+ until it costs 2k gold a turn, then I am less selective.
6) Double stack your stat cards; at the moment the game is fucking horribly balanced when it comes to cards. 10% of the cards are 30-70% more effective then similar sub types. For instance, max crit card gives 5% crit where attack is 40%. Even without knowing exact crit chance/attack speeds you can do the math pretty easy. Now throw in the attack buffs from LS's and in match attack increase buffs (hector, lancelot, gawian). Attack wins by a land slide. I need to test more but I also almost believe the 80% damage to __element damage doesn't compare due to the way damage is calculated (if it has anything for defense then low base attack X high damage modifier = low damage still). I'd basically put 2 attack red cards on all damage dealers unless you have mana issues. The only main exception is a mana battery where you put mana theft (4-5 mp per attack, 40% chance). Put 2 attack speed buff cards on him and watch the mana fly (see item 7). Defense is the same; double defense on almost everyone, the way the game handles defense even a low tier defensive card trumps top tier dodge, hp, bubble, flat damage reduction card. Other exception is going double initial cool down cards on global CC members (cleo, medusa, Morgana, etc). The faster you get a global CC out the less damage you take and better chance of killing one person before they come out. It also doesn't let them use abilities so if they were about maxed it delays them using all the while you are using abilities and gaining time to use another. CC is king my friends as long as you have at least one bad ass damage dealer.
7) Yeti...enuff said. Yeti is the most OP mother fucker around. He has top 2-3 attack speed in game but he is a wizard, wizards do splash damage so it hits all targets in front line. So damage is good if you build him damage but the real trick is to give him attack speed red, and mana theft blue. Insane mana regen from it, now if you have a purple "on hit" ability he is awesome for that (I have mine with a frozen one and frequently freeze the front line). If you don't have on hit you can give him a second attack speed card
8) Try and put any prism cards that scale with hero level on your lvl 60's. 50's make sense in certain situations (max MP one for instance) but you are missing out. For instance, if you had the attack one (1% per hero lvl). Putting it on a lvl 60 gives 60% attack vs the red card which gives 40%....so wasting that on a lvl 50 where you hardly get any more then 2 red cards is not smart. Use your "on crit effect" cards on your lvl 5 high attack folk (mary, van heislenk, yeti are the best 3). If you get a defensive purple, you NEED to put it on Minerva. Makes her so fucking tanky with a second yellow defensive card + her skill. I've killed a team in master arena in 15 seconds flat but her and spent the next fucking 30 seconds 1v5 before I could kill. Jeane is also a great choice but you lose some of its effectiveness due to high uptime on invuln
9) Commit...you might not get the best draws etc but you can't be wish washy in this game, pick a path and commit to it because what ever strat you are going for takes a fuck ton of time to get all the pieces in place so you can't be changing your mind mid way. As I mentioned in the previous post, 3 days ago I had come up with what I feel is going to be a strat that only 1 person on the server can shut me down on and I've been building it since even though next arena is still 3 days out. I can only pray they don't ban archers next round haha. I would love to see a venus targeted ban so we can get away from that bullshit but not a full blue ban since my strat leverages napoleon and morgan for significant skill shut down due to rains.
Anyways, hope that may help a few newer folks trying the game. It has its charm, if the develop it and progress I'm happy that I left Brave Frontier for it (BF is pretty damn well put together in hind sight but at the end of the day I wanted something with a fresh start).
Good luck~