There's too much to cover here.
but here's the main take away points:
This is the market page:
http://ragial.org/vending/iRO-Renewal
You can look up prices and all that stuff. Don't get too hung up on the inflation, I did this from 0 when I started on iRO a year and a half ago and I managed to make it.
Next: leveling spots, as you might not be aware or might be aware there is an EXP penalty depending on the monsters you fight. https://irowiki.org/wiki/Experience
It isn't like before where we can kill anything really strong and get all the exp, so with that, there are the bounty boards: https://irowiki.org/...ty_Board_Quests
they were recently updated so, the zeny reward changed but every 4 you complete will grant you 1 eden merit badge, you can exchange eden merit badges here: https://irowiki.org/...den_Merit_Badge
Important: Beelzebub Fly Wing is an infinite fly wing, costs 5 Eden Merit Badges and they last a week, highly recommended if you're gonna be doing these bounty boards and getting exp from them,
Next: Magical Reset Stones cost 8 Eden Merit Badges, you need a Magical Reset Stone to change to 3rd class. So keep these Eden Merit Badges in mind.
There is also gramps which rewards 1 Eden Merit Badge once you complete the mission and 2 for VIP, here is the gramps page https://irowiki.org/..._Turn-In_Events
It is nice to go with a party, a lot of exp is granted from completing the 400 monster kill missions. Once you get the mission you COULD kill 400 of THAT mob given as a mission outside of the map too. But it is recommended to do it in there, it's usually faster, try finding a party not sure if difficult for mage class.
Again, bounty boards are really good for exp you can do them solo or with a party (or with friends!)
As for the market, look at what is on the Buying Section: http://ragial.org/buying/iRO-Renewal
A lot of stuff might seem hard but there's some notable monster drops that you can sell to players (or you can take the market head on and compete with you own merchant in another account and have it vend.)
Notable NPCs: Eve Natalia, NPC loots to be converted for safe certificates, although most of these are kinda popular and sell for a decent price (whenever you get to them, not everything is to be turned into certificates, but you don't have to worry about that right now:
https://irowiki.org/...afe_Certificate
Eat Gear is also mentioned, so if you manage to make any of those refined items OR make a whitesmith to job 70 to get the refine skill, you could try refining some weapons to see if you can get safe certificates. Oridecon and Elunium are certainly worth something so if you choose a bounty board mission and it has those drops, you can benefit in the long run.
Now for your questions: upgrade gear? Oridecon and Elunium? Unless you mean what is the next gear progression for yoru character. Gear Cards? I ran on eden gear to 99/70, but you will need stuff like phen card or orlean's uniform to prevent cast interruption, raydric card for reducing neutral property damage, variant shoes just because it's good HP/SP at a low cost, Anti-Medium/Anti-Large/Anti-Small cards for say, silver guard or round buckler (as a rebirth class you can wear the round buckler, provides more defense) and elemental armor cards will do you some good. Weapon? I think maybe thorn staff or if you wanna go stronk but risk not wearing a shield you got the http://db.irowiki.or...item-info/2000/ staff of destruction with high matk, orlean's glove and orlean's server are also decent options, but the glove costs a bit. I suggest you be conservative with your money.
Max level? Second Class - 99/50, Rebirth Classes 99/70, 3rd Class: 175/60
You lose 3% exp upon death if you are NOT VIP and 1% if you are VIP.
VIP grants you what is in here: https://irowiki.org/...vers_Comparison
I personally point out: 10 tokens of siegfried per day, you can choose how to turn in your exp at a bounty board (i did both EXP granted (base and job) to be submitted as base, makes base leveling or job leveling a lot faster. You can also take both gramps missions at the same time, non-VIP has to take them one at a time, you lose 1% exp upon death and the warper takes you almost everywhere (you still need to go to alberta to travel to the island cities)
Good way to join a guild is check the guild recruiting forums
Warp to towns via kafra or the eden group officer has a warper on the left side of the map that takes you almost anywhere in the game.
hope this helps!