Doctor Who Legacy hints
First download the game from google play or any other phone app installer. Next play the levels they start you out at. You will gradually unlock team members. Once you save up enough time crystals I would purchase Ianto Jones or Robin Hood or Ace. They end up being some of the toughest characters. Once you unlock River than upgrade her. Continue beating levels and unlocking allies. I would spend any extra time crystals unlocking perks as you will need those bonuses on the expert levels.
Doctor Who Legacy fan area
Personally I am not one to purchase game add-ons but the fan area is a really good buy. You only need spend five bucks and it's unlocked forever. They add to it all the time and you get a bunch of stronger characters.
Doctor Who Legacy strong teams
The strongest teams are teams upgraded all the way and are all the same color with secondary attacks that cover the other colors. My team that I use seems to be able to beat anything they come up against. I use the tardis I unlocked in an expert level, placed in the doctor spot. Next I use expert River. Then expert capt Jack aka the face of boe. The last three are Handles, Jimmy Wicks Granger, and expert Amy. I have the perks set to boost yellow damage and to gain health every time I use an ability. I also gain health and increase damage for every straight line I complete. Capt Jack can use his ability every two turns so I use that to boost my life. Once the others can use their abilities I start from left to right and the end result is the whole board turns yellow and Amy has increased yellow damage by 30 percent. That attack usually kills all.
Doctor Who Legacy expert levels
The expert levels are very challenging. It will take some time, but the rewards are worth it. Below I've included some good walkthrough videos.