**be sure to have a sensitive toothpaste on hand ** i have a tip that a dental assistant friend told me. take a good quality paper towel and cut out a piece and fold it the long way to make strips of "cotton" to stuff under your upper lip to soak up saliva as your whitening your teeth. the less saliva, the less watered down the peroxide gets, therefore maximizing its bleaching power. ok, about these strips....A+....I noticed a difference after one or two sessions. I'm on my third day. the 1st day I did two sessions in a row and one the next day, one today. my teeth are a little sensitive but not too bad. i don't think I could do 10 days in a row. i also took an aleve before hand simply as a way to put the kabosh on any serious discomfort. very happy with results. and yes, the lil white spots on your teeth IS temporary so don't freak out.