It depends how one is using the Jesus Prayer. If one is attemtping hesychasm, they should without a doubt be under the discipline of a spiritual elder. One could also question whether in todays conditions anyone but an experienced monastic should even consider the attempt.
If on the other hand one is simply using it as:
a form of contemplative prayer for 10-15 minutes at a time
or part of a prayer rule like the Optina Cell Rule:http://www.orthodox.net/ustav/the-cell-rule-of-five-hundred-of-the-optina-monastery.html
or as a way of praying throughout the day during tasks that would not allow another form
then it is okay to proceed.
Bishop Kallistos has this to say:
"The invocation of the Name if a prayer of the utmost simplicity, accessible to every Christian, but it leads at the same time to the deepest mysteries of contemplation. Anyone proposing to say the Jesus Prayer for lengthy periods of time each day — and, still more, anyone intending to use the breathing control and other physical exercises in conjunction with the Prayer — undoubtedly stands in need of a starets may still practise the Prayer without any fear, so long as they do so only for limited periods — initially, for no more than ten or fifteen minutes at a time — and so long as they make no attempt to interfere with the body’s natural rhythms.
No specialized knowledge or training is required before commencing the Jesus Prayer. To the beginner it is sufficient to say: Simply begin. ‘In order to walk one must take a first step; in order to swim one must throw oneself into the water. It is the same with the Invocation of the Name. Begin to pronounce it with adoration and love. Cling only of Jesus himself. Say his Name slowly, softly and quietly."http://www.oodegr.com/english/psyxotherap/dyn_onom1.htm#_Toc110013901
As to your questions:
1) Find a church/monastery with a priest/monk experienced in the practice of the Jesus Prayer.
2) Judge for yourself against Bishop Kallistos' advice.
Fr. Deacon Lance