How to open pirate?

Infighters = STR should be your level for equips, rest into DEX
Gunslingers = DEX your level, rest into STR

I would also concentrate on merchanting, so when pirates come out you'll have enough money to buy good equips (which will be expensive in the beginning). I am also buying exchange quest items to EQ to level 30.

According to StrategyWiki...

You got the stats backwards there. Infighters have main stat as STR and Gunslingers have their main stat as dex.