Before practising moola bandha, we have to feel the exact location of our mooladhara chakra (root chakra). For that, two warming-up exercises are necessary: ashvini mudra (contraction of anal muscles) and vajroli mudra (contraction of urogenital muscles). These exercises are quite simple: we do it naturally when we try to hold back the urge to respond to nature's call. Now begins the difficult part: our root chakra is just between these two muscle groups, somewhat inwards. Contract it while inhaling. The proof that you have found the exact location is that all other muscle groups except the root chakra area are completely relaxed, and you feel at the same time the tension between your third eye (ajna chakra/pituitary gland) and the medulla oblongata. The area around the spine between tailbone and brain feels like an unlimited free highway full of vital energy. There are other instant minor symtoms such as unblocking of stuffed nose, sudden serenity of heart, hearing the pulse at the back of the brain and on the right ear, slowing down or even spontaneous stopping of breathing. These are some of my experiences (everyone has his/her own peculiar experiences).
Once you have reached this blissful state, you may integrate your japa (mantra repetition) into bandha. For example: 1. effortless contraction of mooladhara chakra and inhaling while mentally chanting "om", 2. additional contraction of vishuddha chakra (throat) and kumbhaka (arresting breath) while mental chanting "mani padme", 3. releasing all tensions and exhaling while mentally (or audibly) chanting "hum". This is just one example of unlimited possibilities, but a really powerful one. If you add your own spiritual dimension to it, it becomes a mighty tool of illumination.
Doing this aligns sponteneously our three bodies (physical, astral, causal) around the centre of our being. In this state, we are simply whole. Spontaneous healing takes place. It's not a matter of believing, but succumbing to the physical law of a higher demension.
Why not trying it now?