If you are a new(ish) player, there are several resources online that detail out specific aspects of party dynamics, here are the basics:
Building a party:
* Parties generally consist of six members- a tank, two melees who can skillchain together, and three mages, generally divided into a healer, a supporter, and a more offensive role.
* While the mage line is pretty flexible, the melee are fairly rigid.
* Aden's Renkei diagram, the best skillchain chart out there, can be found here.
* "Blind invites" (inviting somebody without asking in /tell first) are considered extremely rude, and will generally be declined. Be polite, and ask first.
Looking for a party:
* Enter your search comment by opening the menu: Search → Edit Comment.
* 〇 means "Yes", × means "No".
Important details are:
* The amount of xp you need before leveling up (your "xp to next level (tnl)")
* The areas you can/cannot access (this isn't really relevant until later).
* The subjobs you have available.
* Please do not harrass White Mages for Raises. Be prepared with Reraise items, or be patient if a White Mage from another party does take the time off to come raise your fallen member(s).
* Do not camp on top of other parties. If the place is crowded, move to a different camp.
* If you must go AFK (Away From Keyboard) for any period of time, let the party know in /party chat before the puller pulls a mob. Keep your away times short, or disband if you must go for a long time.
* While there will usually be a mage to cast Sneak and Invisible to move through dangerous zones, sometimes this will not be possible. Bring the necessary Silent Oils and Prism Powders with you.
* If you want to disband the party, please let the leader know well in advance (15~30 minutes)
* Often replaces party members who need to go.
* When replacing a party member, be sure to check with all other members how long they can stay for, and make sure that your replacement fulfills the same party role as you.
* Generally head down to the campsite first.
* Generally do not replace party members. If someone needs to go, the party disbands.
* Because one person's departure means the end of the party, people are expected to stay for roughly two hours once at camp.
* Gather at the Signet, or the nearest convenient location in town, before moving as a group.
* Before riding a chocobo, everyone will target the stablemaster to lock in a price, but not ride. Once everyone has gathered around the chocobo, someone will say "のります", "乗ります", or "norimasu", all of which mean "ride", before everyone hops on the chocobo simultaneously.