How can i improve my running soccer skills?

i am doing soccer for a sport at my school.
& i’m a right midfielder.
it’s obvious those do the most running.
& i have been playing soccer for the past 10 years.
but this year i’m in the varsity team & it’s tough.
any ideas on conditioning?
for soccer?
and i need help with preparing myself for a game.
how to calm myself.
& be able to use my skills without messing up.
i need help.
asap.