Originally Posted by landarc
It is likely that you added enough cold briquettes, that they intially threw off some poor smoke. You want to manage your fire so that you are never adding a lot of additional cold fuel mid-cook. Adding a little bit, more often is best.
^ +1 Like Landarc says, manage your fire so it is consistent... You can also preheat the briquettes by placing on top of the firebox (or cooker).