wait until you have the airship to play blitzball and get brother (airship bridge) as midfield, tidus as front player, wakka as front player (airship bridge) and naida as defence (calm lands shop).
maybe you want to get jumal too, hes somewhere in luca, cant remember where, though. hes a good keeper.
just use google
woth tidus, brother, wakka and naida you shouldnt face any problems.
brother alone is so fast that he shoots about 5goals each game without even beeing stopped by the enemys defence (they are too slow to catch him^^).
later on i would pray, that the al bhed psyches dont extend eigars contract.
if ur lucky and hes a free player, stop playing blitzball asap and search for eigar on the airship.
he is the best front-player there is and you can swap him with either tidus, or wakka.
i have wakka and eigar in the front and brother in the mid and most of the time the other teams dont even get to my defence or my goal, since brother and eigar stop them, get the ball and shoot one goal after another.
do not play blitzball while you still have the normal besaid aurochs! all youll do is loose and give exp to the other teams.
if you are able to read german, i can give you a link to a german gaming-site, which has lots of different teams and tactics listed and a list with all blitzball players and where to find them.