I can't answer that question for you. Regardless of what anyone says online or in other FAQs about the game, your species and job(s) are really up to you. Depending upon what your ultimate goal in the game is, some combinations may work better than others, but honestly, if you work at it, you can make any combination work.
The only rule of thumb I can give you is this: Pick a species that interests you. Once you have that, you can easily try out different jobs from your Mog House. The species and gender are pretty final (unless you want to delete and start over) but the jobs are not.
I actually also recommend trying out a number of jobs. Sure, it can make levelling up your main job take longer, but it really can help you find a job that best fits the way you play the game. Plus, it never hurts to get more items, increase your bankroll, complete quests and missions, and bring up skill levels along the way ;-)
I have a Galka mage, a Taru monk, or something else non-traditional, and people harrass me about it. Should I change?
I actually address this in the FAQ - Maior, but my answer is: screw them. The simple fact is that this is a game, and your goal is to have fun with it. As long as you ae having fun and enjoying your character, then who cares what some dork thinks?
Now, these species do have specific traits that make them better suited for certain jobs. For example, Taru can gain the most MP as mages and Galka can gain the most HP as Warriors. However, I have seen some amazing high-level Dark Knight/BLM Galkas that will scare the pants off of you. And I have seen some spunky little high-level Taru shooting arrows or wallopping critters. So working with traits that don't exactly fit in the beginning with your job can actually pay off in the end.
That being said, when you do pick some combination like these, you do have to ask yourself why you are doing it. If your goal is to have the ultimate "super character" that's a black mage with summoning abilities and paladin strength, well, prepare to be disappointed. The game is designed to be much more balanced than that, and you will still have to play off your party member's strengths.
If you discover you don't like the combination, no biggie. Go to your Mog House and change jobs. Just please, please, PLEASE don't change just because some close-minded idiot tells you to.
One more thing to mention in this rant, there are some quests which actually require you to be certain things. So, if you really want to complete these quests you may have to combine strange races and jobs.
But everyone tells me I'll never be accepted into a party as a Galka mage!
This is the argument most people harassing others about their species/job choices fall back on. It is simply not true.
As of Jan. 04, 2004, there were over 1 million people playing FFXI. Since the PS2 HDD release in the US, I'd wager that number has shot up considerably. This means that there are plenty of people online for you to party-up with. If you can't find a party as a Galka mage or a Taru theif with this many people online, then there's got to be something else that's wrong (like you're not really playing the game or have some strange version of Turrets Syndrome for keyboards.
I'm freaked out! What if I make a job/sub-job decision I wind up not liking?
Well, you can always switch ;-) People do it all the time. I've known level 50 WHMs switch to MNKs just to try them out. Don't worry, you're free to switch whenever you want.
In fact, I'd encourage switching around a bit, especially in the beginning. It just lets you get more of a feel for the different jobs and helps picking one all the easier.