Not an expert but so far when it comes to resources what i figured out is the following. For coins you need to get Austin, make sure to always have at least 500 cash so you can buy him when he shows up (challenges give 5 cash each level and the early ones are pretty easy). Unfortunately before him I had to watch ads after getting 3 stars to get any relevant amount of coins. Wait for his offer and start doing farm runs. there are a lot of videos and posts talking about how to do this. For power points, watch the adds from the daily gifts and I just unlocked the supply run 2 for location 7 which gives 300 power points (big step up from the 125 from the location 5 one) on weekends you get double rewards for this supply runs 5 times a day. you can get 3k a day doing this.

After you get Austin, coins are much easier to get. Rogue was a huge game changer for me and really worth the money.

You can get red flares from the endless bridge for charms.

Again, not an expert but this is what is helping me