Yes, it is true that we may be able to see the future during sleeping or meditation but usually it is given as a cipher, something for us to decode, a representation of something. For example, You had a dream that you are riding on a boat towards a dark tunnel, there are many meanings to this and usually it is only the person witnessing the dream or vision itself that decodes it entirely.
Random? If you keep persevering with meditation it will appear in random intervals, I usually get visions the first 10 minutes of meditations since I have persevered everyday to sacrifice some time towards the activity. Some people regard dreams as a message and this is true however for me as Aleister Crowley said in Book 4 "The best kind of sleep; is a dreamless sleep" and so my visions or premonitions only come in meditation. If one does not wish to persevere in the art of meditation which I stress because of its importance then you can proceed with scrying.
Scrying is the art of divination through a medium usually a black mirror, scrying bowl, etc. Some people use it as a medium to "contact" other beings, or rather different aspects of the "mind". Scrying is a very fun experience and it is a very true phenomena, no matter how skeptic the person is. Scrying is basically looking into a black mirror so that you may get a vision of anything you want or need for that matter, if you have a question then focus on it while performing scrying. How the "message" comes to you is basically round off in 3 ways, either you may see a sort of "video" or moving picture within the scrying mirror, a picture within the scrying mirror, or it may go directly into your mind (There may be more ways but these ways were the most common.) Still, one needs to practice scrying with perseverance as the same with meditation, When the time comes that when you gaze upon the darkness of the mirror with the vision of your face gone and all you see is darkness, that is the correct way, and when you see a misty cloud that comes forth from the mirror into your vision, that is the correct way.
"IN LVX et 93"