Theme. I am playing a lot of Greyhawk, and its perfect for because its so fleshed out that you almost have to have a theme to get anywhere. I have all the old stuff, so if you need to generate a place of birth, racial mix, etc. its all there, as is all sorts of background stuff. Creation goes like this
1. Figure out rest of group, I usually just let other players pick class and role they want to play and then fill out group with whats needed. This group had a human Crown Paladin, a half elf Monk, and a human Conjurer (in game brother of Paladin) who was starting out as a Knowledge cleric. The group needed some healing, some second line support, some social skills, i.e. a little of everything which screams BARD.
2. Class is above, so I pick race next. Race I usually fill out to make the group approximately represent the racial mix of world at large. Everyone wants to elf or more exotic, it seems like I get to play a lot of humans, dwarfs and dragonborn. The group above is very normal, so I picked Dragonborn to stand out in the game world.
3. Think of a concept with something a little odd about it -to avoid a min/max approach and also to give the PC a hook. My 2nd or 3rd best ability score will go here, we roll for scores. Example is what I am playing now, Dragonborn STR based Bard. My idea was Dragonborn Bard who started out as a Sorcerer due to parents/social structure who really wanted to be a warrior like in legends and myth. Needed a reason to 'quit' being a Sorcerer after first level and I thought being huge and strong and thus "miscast" would work. That means high STR, with CHR second and CON third.
4. Think of background story that fits. - For Dragonborn in Greyhawk its a new race, so I put origin on Dragons Island, a land ruled by a dragon prince. Its far outside the World of Greyhawk as first laid out in 70-80s so it explains not being seen before. This of course plays right in Far Traveler background. We are playing Age of Worms adventure path, so DM suggested Storm Sorcerer as a fit as Wind Dukes of Aqaa are involved and someone needed to speak Auran language. From there it flowed that visions and portents had caused me to travel far from home to the town where the Age of Worms started. Also, since Dragonborn are unknown in this part of the World I figured I would try to take those Dragonborn feats in XTE to show these foreigners the majesty of dragonborn
5. We rolled and I got somewhat lucky 15,14,14,12,10,10. I need to have 2 odd scores to take those dragonborn feats, and with dragonborn bonuses of +2 to STR and 1 to CHR but needing to have higher STR then CHR for RP purposes I put 14 in CON, 15 in STR, 14 in CHR, then 12 in DEX and 10 in mentals. I realize this is a bit odd, but it fit the concept. I was going to put the 12 into INT instead of DEX to reinforce the concept, but realized I had no Dragonborn mini with a shield so I probably wont use a shield. I do have the Dragonborn Paladin mini with a great axe/halberd and medium armor, so I guess I wont use a shield. An even CON score means Warcaster is in my future to handle weapons and cast and use spells on opportunity attacks.
6. Far Traveler is the background, so what fits with above is
a. "I have a strong code of honor or sense of propriety that others don't comprehend."
b. "I honor my deities through practices that are foreign to this land."
c. "Adventure. I'm far from home, and everything is strange and wonderful! (Chaotic)"
d. "The gods of my people are a comfort to me so far from home."
e. "I am secretly (or not so secretly) convinced of the superiority of my own culture over that of this foreign land."
This flaw is key, as a Bard it means I am constantly telling these staring, astonished people how my people are strange and wonderful and majestic compared to them.
7. Flesh it out from there. Storm Sorcerer with melee potential means booming blade, never using shield means shield spell. AC will suck until Valor Bard comes online, so that means Halberd to try to stay away some as well as bonus 10' move by casting spell. STR will be higher then CHR, so try to squeeze most use out of Booming Blade by taking Warcaster to use it on Opportunity attacks and forced movement with dissonant whispers and command from paladin and MC wizard. Spell selection needs to favor spells that don't have saves or are flashy, showy type stuff like Heat metal and polymorph but this isn't a subtle, enchanting type Bard so Suggestion (help us kill your boss so you can take over) and fear make it in. Animate Objects and Destructive wave will make it in later. For Suggestion ideas watch "Gods of Egypt" for Elodie Yung as Hathor using it.