eek its been a while since I started off.
Anyways I think the main deal is just make sure you have a good party set up, everything else should come naturally if youve played a lot of RPGs (which you have of course

)
The party I used that got me through the game perfectly well was:
Front: Landsneckt (or whatever its called), Protector
Back: Medic, Alchemist, Survivalist
You can swap the Survivalist for a Troub if youre after a more advanced strategy.
basically the protector is necessary for the 1st few floors to soak up front row damage (he has good defense buff skills too) , as is the Alchemist to deal damge to FOEs (fighting classes dont deal shit all damage to those guys). Have your Alchemist focus on one element initially (fire is good)
Skills should be self explanatory.. its easy to tell which ones would be useful. Just make sure you get Medic's 'Immunize' pumped up ASAP.Its invalubale defense buffing against bosses, and it will serve you really well through the whole game. Fighters should focus on skills like: Appolon for survivialist, Crush for landswhatever.
A good strategy I used was save skill points as I leveled up and then focused on what was bringing the party down in battles, then assigned points accordingly to rectify the problem. Easy