When you advance in meditation you can see your Ishta Devata in physical form. Lord Vishnu will give you Darshan with four hands; Lord Krishna will appear before you with flute in His hands; Rama with bow and arrow in his hands; Lord Siva with trident and Damaru.
Sometimes the Lord will come before you in the form of a beggar or sick man with dirty rags. He may appear before you in the form of a coolie or a man of low caste. You must have the keen sense to detect Him. Your hair will stand on end when you meet Him.
He appears in your dreams. Lord Ganesha comes in the form of an elephant in dreams. Devi appears in the form of a girl in your dreams.
During deep meditation you will have Jyotirmaya Darshan. You will behold a huge pillar of light. You will see infinite light and you will merge yourself in it. You will be struck with awe and wonder.
If you worship Lord Krishna intensely and constantly, you will see only Lord Krishna everywhere.
A Yogi should always avoid fear, anger, laziness, too much sleep or waking and too much food and fasting. If the above rule be well and strictly practised each day, spiritual wisdom will arise of itself in three months without doubt. In four months, he sees the Devas; in five months, he knows (or becomes) Brahmanishtha and truly in six months attains Kaivalya at will. There is no doubt.