How to reduce slow starts at the beginning of the game?
Don't forget, you get a resource card for each resource you touch when you place your second settlement.

If you're still finding things going slow, here's some random ideas you can use:


For each player, remove a Year of Plenty or Road Building card from the deck, shuffle them up, and deal one to each player.  That should get things really going.
Give each player one extra road as suggested.
Let each player pick one extra resource when starting.
NEW - The first time any player rolls a 7 (i.e. this will only happen once), after placing the thief the player has the option of taking a resource from the pile matching the tile they just played the thief on instead of taking a resource from a player (yes, it rewards a little bit of luck, but it also softens the blow of the first thief a little).  
NEW - The first time each player rolls the dice in the game, if they get any resources, they may take one extra of a resource they just received.