For extra health, all you have to do is find a beautiful woman and look at her through the scope and you'll recover health. The women with the nurse's outfit will recover more health.
Another way on EX (in Silent Scope 3) is to get as many headshots as possible and your health will increase by 3%. If you get an SS rank, you get 20 extra health after the stage is over. (NOTE: the grade is effected by how long you take.)
GamesRadar is the premiere source for everything that matters in the world of video games. Casual or core, console or handheld - whatever systems you own or whatever genres you love, GamesRadar is there to filter out what's worth your time and to help you get even more from your games. We deliver the best advice, the most in-depth features, expert reviews, and the essential guides for all the top games.