Do a nice job, be respecful and have a nice sense of humor. Listen to people with experience and make some friends along the way. You will gain some good professional experience and see some interesting stuff.
Leave the semi-significant other, leave the car, take a job that none of the long-serving slugs like, such as WestPac or the Middle East. Bank the money, learn your job and then the Second Mate's job, ask lots of questions, and stay out for a minimum of six months for your first two tours. After just over a year with MSC, you will be ready to get the Second Mate license and actually do the Second Mate's job.
Come back after vacation and upgrade, repeat, get them to fund your upgrade classes to Chief Mate. Once you have your Chief Mate's license and have paid them back in time served for the training, figure out what you want to do.
A good friend of mine has been with MSC since he graduated around 15 years ago. He's had nothing but problems with reliefs. Twice he's been onboard for over a year without a relief. To answer your inevitable question, he stays because of the money. Each day you don't get a relief MSC pays an extra amount of money (I'm not sure of the exact amount).
Basically if you want to knock out sea time quickly and are willing to give up a personal life for a while than MSC is the way to go.
Is it overwhelming first going to the ship and reporting onboard?
Well, it has probably changed since I sailed with MSC back in the 80's, or maybe it hasn't. Don't know.
As I was in the chief mate's room handing over a sheaf of papers before I turned to aboard USNS Pawcatuck in Souda Bay, the mate had to excuse himself for a moment as there was some commotion outside in the passageway.
Seems there was an AB running for his life as an oiler chased after him while brandishing a fire axe.
Something about cheating while playing cards...I never got the full story and didn't ask any questions.
I worked for MSC as 3/m after graduation on a couple of different ships over the course of a year. Overall it was a good expierance and a good way to learn the ropes and cut your teeth as a brand new third.
But I saw the writing on the wall and got out and moved to greener pastures. Get in, make some good money, get some good exp., do a quick upgrade,and move on before you get sucked into the system. Learn as much as you can.