So you have four different types of abilities to use: Attacks, Maneuvers, Moves, and Special Moves.
Attacks, Moves, and Special Moves all take up the same combat slot, so you can only do one of any of these at a time. Usually you use them to get yourself Blue bar, such as with Slide, Red bar, such as with Flex, or initiative points, such as with Charge!. You can do other things but lets focus on those for now to keep it simple.
Maneuvers are considered passive and defensive so they can be kept on at the same time you're using an attack, move, or special move. Maneuvers can also give you Red bar, Blue bar, initiative, etc.. This means you can earn at least twice as much Red bar, Blue bar, or initiative as your opponent if you are using Maneuvers. Unlike moves, maneuvers go off whenever an opponent does something to you. If an opponent uses Charge! against you while you have Oak Stance up, for example, you get Blue bar.
There's just one maneuver you need to be really careful about. Blood lust gives you Red bar but in exchange your defense is cut in half while it's active. Never have blood lust on when your opponent is about to attack you.
So the general idea is to use moves and maneuvers to get yourself up to 6 Initiative so that you can utilize Flex instead of Jump. Most people use Charge! mixed with Oak Stance or Death or Glory to get their initiative up fast. Feel free to switch your maneuver to whatever you feel like you need at the time. Spend Red bar to maintain a good Blue bar as you're raising initiative.
http://ringofbrodgar.com/wiki/Combat:_A ... _Maneuvers