A lot of this character was predetermined in regards to class and back-story. The group needed a healer. Since we are playing by 3.6 rules [my home-brew rules for D&D 3.5], all we really need is a character with access to the 0-level cure minor wounds spell (3.6 allows for an infinite number of 0-level spells to be cast each day). Still, knowing we were going to play an updated version of the Dymrak Dread, I felt we should have a character who was able to turn undead, so I chose to play a cleric (that, and the DM had been planning on running an NPC cleric had I decided not to join).
I rolled up a character using a very player-friendly method: Roll 4d6 and pick the best three, reroll any ones, and roll seven stats and pick the best six. Even so, my character ended up with lower total stats than most of the other party members. I placed the highest rolls in wisdom and charisma (I like playing high charisma characters), my mid rolls in strength and intelligence (I love skills, even if I largely only use spot and search), the next lowest in constitution, and the dump stat in dexterity (I was guaranteed that he could have full plate mail which makes dexterity not count for as much).
I apologize if I bored anyone with the mechanics, but they are necessary for me to think about as I'm designing the character. They give me an idea of how strong, wise, good-looking, etc. that he is. It's at this point that the fun begins for me.
One of the first things that I determine is what sort of accent I want to use. Now, I'm terrible with accents, but they usually help with building my character. I also like using accents when I game so it's clear to everyone whether my character said something or if I, as a player, was just making a comment. I knew that my character was from the fantasy country of Karmeikos, which has a Slavic-esque feel, so I chose a light Russian accent (my heavy Russian accent is reserved for orcs and innkeepers).
With all of this in mind, including some notes from the DM, I decided to build my character's personality as a charming (which I haven't pulled off that well), chivalrous character similar to the ex-Russian spy in the movie RED. He appreciates good food, good wine, good music, and women (not necessarily just good ones). He is loyal to his friends and the wrath of god (in this case Mithras) on his enemies.
Even though we started playing, I still haven't fully fleshed out poor Dimitri. Due to the other characters, I decided to make him a bit more of a tank, which meant giving him the war and sun domains. He is the wall of steel that keeps evil away from the innocent (or at least his other party members). I am a little concerned that I'm going to end up playing him as the standard "good guy" cleric, so I'm working on building a couple of faults into him as well. I just need to be careful that the faults don't become the character.