Tips pretty much everyone should know; even more proficient players.
So here are a few things that I picked up on that have made the game insanely easier for me. These include how to use champs and a few good mastery options.
1: Wolverine should never use special attacks. Just save your power and a r4 wolvie even unduped regens 100 health per tick. He single handedly (except for SL on bosses) took out Act 4 with no health down. He can also last forever in RoL; I beat WS and CM with no health down at the end.
2: Max out parry and stupefy asap! I learned this during webslinger, and it saved me a ton of units. Evasion champs can't evade when stunned, and with both masteries maxed, you can get a medium light light medium combo in, then parry once more. It makes all evasion (except stun immune) champs easy.
3: Crossbones's fury is OP. Not only do they get him hitting like a 18-wheeler, if you get 5 stacks; ability accuracy is gone: no evasion, no arc overload 2.0, you name it.
4: Never ever ever ever EVER sell champs. Most people already know this, but I see new players throw away their r4 3* so they can pull SG 4*. Selling 2* isn't too bad, but it just resets all your progress towards max sig crystals.
5: Unless you want to kill global, don't talk about politics. It makes it no fun. Seriously.
6: Ask before awakening or ranking up your 4*. There will always be someone smarter than you in the game, so listen to their 2 cents before wasting a gem on NC AV or Mordo.
7: How to kill almost anyone with GP. I'll start with the exceptions: bleed immune champs, passive damage dealers (Abom Electro Cable), ability accuracy reducers/nullify-ers (BW KP CB AV) and evasion champs (unless you have a 50 hit combo). So, what you need to do is build up to your L2 and hit him with it. Keep him bleeding to refresh your power lock. Once he has less than a bar of power, get him into a corner and spam your heavy. This works most of the time and really helps, even if it is really tricky to do. The biggest thing is to be patient and wait for things to fall into place. Look up more on this from YouTube.
Well, those are my thoughts. Any questions or other tips that help people?