The First
First, Beginning, Outset
noun, の adjective
The most first thing is the first thing.
さいしょ
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
最初はとりあえず生で！
I'm gonna start with a draft beer!
コウイチの最初のかの女の名前はコウイチ子でした。
Koichi's first girlfriend's name was Koichiko.
お前本当に下手くそだな！初心者でもこんなに下手くそじゃねぇだろ。俺が最初にこのゲームをプレイした時は、お前よりずっと上手かったわ。
You’re awful at this! Even a newbie couldn’t be that bad! When I played this game for the first time I was way better than you.