I'm gonna head to dunes, this is my first character since 2002 lol.
Playing a warrior.
What is the basic requirements/needs for joining a party? Like gear wise, do I need food or potions?

Just wanna be as prepared as I possibly can be as a new player going to the dunes lol.

Bring a weapon (I'd recommend a Great Axe if you're going WAR, grab the one just called "Great Axe" if you can, I think it's about 3k from a vendor in Selbina), cheap armor is fine, some food is nice (meat jerky is pretty cheap and handy at low levels, or if you can, jack-o-lanterns are amazing- though those can be pretty pricey for brand-new players), try and solo up to around 12-13-ish first if you haven't already. Don't worry about potions, though later on you'll probably want to have some Silent Oil and Prism Powders on you (or some other method to sneak/invis yourself, like monomi and tonko if going /nin, etc.). If you want a better shot of getting picked up fast, go stand around up at about (D-7) in the North-east-ish area with your flag up, since that's where most of the early-Dunes-level groups will try and party first.

Other than that, don't worry too much about "keeping up appearances" on your very first Dunes-level job.. Sure, there will be elitist buttheads that'll just say "go farm and get better gear, scrub", but the fact is that there really isn't much you can do to make yourself better prepared until you can go nuts with HQ gear, have a merit (or two, for when you hit the 20's) already racked up from another lv75 job, etc.

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I'd put cool pics of my achievements/items here, if they were anything interesting. How about "I pooped today! \o/"

Thank you, right now I'm farming some fire and wind crystals and silk thread. Plan on getting at least full scale mail set and maybe a copper ring or the def ring lvl 10. might splurg and get a rabbit mantle haha.
What kind of food though, jerky?

https://ffxiclopedia.fandom.com/wiki/Meat_Jerky
This stuff is generally pretty cheap (pretty sure you can get it from a vendor for cheaper than AH prices) and works well for low-level jobs. Silk thread is great money, and assuming you're around Windurst you can also farm beehive chips and use whatever Fire Crystals you get and buy cheap distilled water from NPCs in town to turn the chips into Beeswax for decent money (and hey, you'll level Alchemy a little bit in the process!), or just sell the chips and fire crystals outright for decent money, Crab Meat NPCs for more than you'd expect, and they're all over around the oceans, etc.

Most of the above (and much more) are discussed in more detail in Cilarnen's great post about making gil starting out:
viewtopic.php?f=6&t=756

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o/

I'd put cool pics of my achievements/items here, if they were anything interesting. How about "I pooped today! \o/"

Super helpful, thank you!