Are there any signs which indicate that one is ready for the path, especially if one has no spiritual teacher?
Yes, the most important indication is a perfect equality of soul in all circumstances. It is an absolutely indispensable basis; something very quiet, calm, peaceful, the feeling of a great force. Not the quietness that comes from inertia but the sensation of a concentrated power which keeps you always steady, whatever happens, even in circumstances which may appear to you the most terrible in your life. That is the first sign.
A second sign: you feel completely imprisoned in your ordinary normal consciousness, as in something extremely hard, something suffocating and intolerable, as though you had to pierce a hole in a brass wall. And the torture becomes almost unbearable, it is stifling; there is an inner effort to break through and you cannot manage to break through. This also is one of the first signs. It means that your inner consciousness has reached a point where its outer mould is much too small for it—the mould of ordinary life, of ordinary activities, ordinary relations, all that becomes so small, so petty; you feel within you a force to break all that.
There is yet another sign: when you concentrate and have an aspiration, you feel something coming down into you, you receive an answer; you feel a light, a peace, a force coming down; and almost immediately—you need not wait or spend a very long time—nothing but an inner aspiration, a call, and the answer comes. This also means that the relation has been well established.
Ref : Questions and Answers 1950-1951