THE FIRST AND THE UTMOST IMPORTANT THING
You can't just know what the strategy is - you have to be able to implement it. Don't race through the game from mission to mission. Take your time doing side missions, exploring, practicing. Run a LOT to build up your stamina. It really helps! The better you know each town, and know how to drive from place to place, the easier the missions are.
My gaming experience says this.
