What particular advice are you seeking?
Generally…
Level up your 3* heroes first to give yourself a solid first team choice in order to gain resources for those eventual 4* and 5*. The first hero of a higher * level can help you build future teams around to progress further in the story map stages.
Keep hero summons expectations in check. The odds are posted, and those 5* heroes can be very elusive even for those who spend money on gems to summon. Due to the ‘gacha’ system there are no guaranteed 4* or 5* heroes except for very specific tokens. If you don’t intend to spend money, there are suggestions to save gems for a 10-pull (there’s a small discount). Ideally you save those gems for newer hero portals.
If you do intend to spend a bit, VIP is a solid purchase. An extra builder will help you upgrade buildings faster. Do not ignore storage buildings; they aren’t glamorous but they are essential. Ideally, you’d want to unlock Hero Academy level 10 as early as possible. I would ignore Path of Valor for now until you see where you are with the game and progress.
Find a good fitting alliance (as EatMyFace suggests) to make progress. Titans are a good source of loot, though at times underwhelming. Your team mates can aid and support you further.
With titans, hit the weak spot (or as close to it as possible) and try to survive. Arrows are very handy.
Don’t worry about raid trophies.
Like all other match-3 puzzle games the boards are random. This randomness permeates the entirety of the game including hero summons (to much annoyance for many), and even loot drops.
Most importantly: Have fun! 
If the game is no longer fun for you, drop it and find something else which is fun.
I’m sure there’s a ton of stuff I’ve missed… A couple of threads which may be of interest: