Rule of 6
Consider writing a short background of your character for when he is between the ages of 3 and mid-adolescences (the age can change depending on the race). Once you have a decent fleshed out background, you need to select 6 distinct parts that played in your upbringing before you studied for your Class. There’s are some exception with instruments and languages, but for the most part focus on getting 6 distinct things you think would add flavor to your character.
Questions you should be asking:
Who are your parents?
What are their trades?
What do they aspire you to do with your life?
Did you have a happy home-life?
Did you have siblings?
What did your family teach you that made you more skilled in your day to day?
What did you do for fun?
Where you cautious or daring?
Did you spend most of your time outdoors or inside?
Did you lead or be lead?
Did you have any unusual twerks from your friends?
What did your childhood friends teach you that made you more skilled in your day to day?
What did you do for money?
Where you rich or poor?
Did you learn from watching or have a mentor from a young age?
Did you exploit your friends and/or family?
Did you hurt or harm yourself or others at a point?
What did your work teach you that made you more skilled in your day to day?
Outside the box?
Most of the typical options can be covered by one of the skills in the skill list of your character sheet (Athletics, Acrobatics, Sleight of Hand, Stealth, Arcana, History, Investigation, Nature, Religion, Animal Handling, Insight, Medicine, Perception, Survival, Deception, Intimidation, Performance, Persuasion) and are covered in detail in the Player’s Handbook (pages 174 – 179).
However, there are several other types of Proficiencies not often talked about;
Did your character grow up at sea, quite possibly you learn how to sail on a boat or ship. Proficiency: Water Craft
Live in the countryside in a Nobles estate, or have a father in the military, chances are you learn how to ride on horseback! Proficiency: Horseback
Maybe you learnt a thing or two about caravans or carts from your gypsy mother or merchant family. Proficiency: Ground Craft
Tools of the Trade
Now most people think of the Mason’s Kit or Poisoners’ Kit in the Player’s Handbook, but this also extends to Thieves’ Tools for the budding young thief or even just someone who’s learnt about locks, say a Trap maker or Blacksmith. Speaking of Blacksmiths you can actually get a Blacksmith’s Kit which is pretty much a fold up bellows with a coal bed and lots of blacksmith tools.
Ah see the beauty of instruments is that they brighten the mood and atmosphere of any party. You don’t need to be a Bard to use them, and because of their lower entry into proficiencies you can select two instruments to be proficient in for the price of one!
Gift of the Gab
Finally we have the most important skill, language. There’s a quite extensive list of languages available in Toril, but once again, two for the price of one to pick up when young. If you can’t quite decided on which ones don’t worry; you can either talk to your DM for some helpful tips on where your campaign is, or wait until you figure out your Intelligence score to pick up some extras (for each plus modifier you can pick an additional language for free);