The story starts at candlekeep, with your equipment beginning with a quarterstaff and some gold. Enter the inn and speak with the shopkeeper and purchase a weapon and armor.
Once you have your equipment, you may enter the inner courtyard and speak with Gorion to commence the first chapter. However, there are a few item fetching sidequests you should take before continuing.
In the inn, you may speak with Firebeard. He wants you to get a scroll of identify from Tethtoril, who is located in the inner courtyard. Tethtoril will give the scroll, and you can return it to Firebeard.
To the north, you should find the barn where the cows are stored. In the hay pile, you can find a book to return to Phlydia, who is located in the northwest corner.
Dreppin, the barn master, will ask you to retrieve the antidote from Hull who is at the front gate. Hull will direct you to the barracks to collect the antidote.
While collecting the antidote, Hull will ask you to collect his sword. This is also located in the barracks.
Within the barracks, Fuller will ask you to purchase some extra crossbow bolts. These may be purchased from the Inn.
Finally, there is combat practice available. When you are near the south of Candlekeep, you will be approached by the Gatemaster, who may unlock the door to the illusionist. Enter, and the illusionist will provide illusionary monsters that you may fight (with assistance from five other temporary companions). When you are finished with the training, the building will close off because of the potential danger of later illusions.
After all desired tasks are complete, let Gorion that you are ready to depart. He will not provide useful information on why travel is needed, but in case he falls, he described two contacts that you meet Jaheira and Khalid found at the Friendly Arm Inn.