Buy yourself a month omega gametime from the CCP games site. Buy yourself a Plex from the CCP Games site (or one of their few authorized sellers such as amazon.com or markeedragon games - unauthorized “gold sellers” might be cheaper, but you might get your account hacked or messed with dealing with some unauthorized ISK dealer. Plus buying from “gold sellers” is bad for the game overall.) and sell it on the market ingame.
Then you’ll have plenty of ISK for quite a while to start with and you also won’t fall into the trap of grinding frantically to afford a Plex to activate for a month’s gametime so you can grind frantically for the next month’s Plex.
Do all the good suggestions above because you want to check them out, not because you need ISK.
Do all the career agents to check them out.
Consider joining a corp.