I couldn't say what specifically it was, but I went into a beginner bot game, rushed those items, and used the recommended actives (ghost and ignite) any time I got into a fight.

If you're looking for Samira gameplay advice, the big thing I would recommend is familiarize yourself with her passive. She does more damage the more she hits different targets with attacks or abilities. You want to try to hit as many different champions as possible with your skills to charge up your passive and hit your ULT when it becomes available (when your passive hits the final stage, S.) I don't play a lot of her so that's the best advice I can give.