I’ve been getting good results by playing at visualising what type of post will come later today (white or buff envelopes, any catalogues or junk mail) and also what kind of dogs we’ll meet when I walk my own, and I like this because it’s a laid-back thing and not the hard “pass/fail” of doing playing cards (red/black) and so on.
So far I’ve been reasonably accurate and getting mnore so, I’m also getting very good for the feel of the boxes in the British version of the game show Deal Or No Deal, I can usually kind-of “see” the cash number it’s going to be (large or small, sometimes specific numbers), although this is with only seconds from when it’s chosen, to when it’s shown, so there’s not much practical use there apart from as an exercise.
I’ve done better trying to “see” the type of number than simply guess red or blue, which you’d think would be easier.
But I don’t do well with pass/fail concepts and one of my working theories is that when you introduce what I call binarity (to hijack a word that exists anyway for my own concepts) you create a manifestation pathway for failure by conceptualising the existence of a probablistic outcome, instead of the willed one, and then giving reality only two pathways to choose… insert some vaguely quantum physics-flavoured thing here about collapsing waveforms, but anyway, that’s my thinking right now. 
Anyway, whether or not that’s a valid idea, that’s why I prefer the variety of this method, and I thought I’d pass it along!