Marihuana does not cause paranoia. Paranoia comes from a result of prohibition.
First time smoker associates smoking marihuana with a BAD criminal, breaking law, negativity, anti-religious .... bla bla bla images and the result is paranoia. If you do try it: Stay calm, focus on yourself, try playing a guitar if you play, work on your computer, try painting if you paint, really listen to the music loud and clear, do yoga if do yoga, have sex. Try to do more complex activities later when you get to know more how you react and function with the effect of cannabinoids, then do whatever you like to do and just enjoy it. Mitja.G