Hi all,
I've made a new players gil guide here: http://www.youtube.com/watch?v=X4hvMV6nzvg
My advice is as follows:
1) Convert unneeded gear into materia and sell it.
2) Do not repair gear unless its at 0% condition.
3) Sell unneeded quest rewards.
4) Unlock the Challenge Log at level 14.
5) Finish the main scenario to guide you to level 50.
6) Do not buy anything from market board or vendors as quests will provide.
7) Use your retainers to sell items and control your bag space.
8) Set a minimum gil balance for yourself.
9) Use the dungeon roulette every day.
10) Once at level 50 and with some gil start crafting.
The video description is a lot more detailed then what I can post here.
If you have any other way of making gil as a new player let me know. Hope it helps.
~ Mithrie