What a signal is. The players passing to you have already seen every card that reaches you. If a strong card in some color is still in the pack at pick 6 or 7, those players are probably not in that color. That late card is a signal. If they aren't taking the color now, they probably won't take it later either, and you'll keep getting it. That color is open.
Watch the players on your right.
- Packs 1 and 3 come to you from your right. Signals from your right matter most, because they cover two of your three packs.
- Pack 2 comes from your left, from the players you fed during pack 1. The colors reaching you may look different for one pack. Don't panic and switch, because pack 3 brings back the players who passed to you in pack 1.
What counts as a strong signal.
- or a top uncommon still there late. Online drafters take Crude Bent Blade, Pinecone Strike and Bothersome Noisemaker around pick 3 or 4 on average. If one of them is still in the pack at pick 7, the players to your right are probably not in that color.
- A pattern over several picks. One late card can be an accident. Maybe the player before you took a rare from that pack. Seeing good black cards in three picks in a row is a signal.
- The . At pick 9 (with eight players) your first pack comes back. If good cards of one color are still in it, the other players are probably not taking that color.
- What you passed. If you passed a great blue card at pick 2, the player on your left may have moved into blue. Expect less blue in pack 2, when that player passes to you.
At a beginner table many players grab rares and big, flashy creatures and let removal and cheap creatures go by. So a late removal spell says a bit less about colors at your table than it would online. Look for the pattern, and take the removal either way.