The second skill (as Crowley says) seems to be to know when you have interpreted the smbols correctly, because most of the time, specially with classical forms of divination like tarot or i ching, you get SOME kind of information. It seems important, however, to know when such information can be considered correct, we all should know some times divinations fail....
Yeah, I never focused the problem this way.
If you discovered something in this direction please let me know.
Meanwhile I tell you this.
A friend of mine, a natural sensitive (who decided not to explore her skill), sometimes read tarots to friends, just for fun.
Form a complete tarot pack she decided to take only major arcanas, because, she said, too many cards were dizzing her.
This suggests the strategy of using reduced set of symbols (Futhark, Major Arcanas,...) and to let the mind (ot the mind's eye)
do the rest.
What "the rest" would mean, still I cant' grasp.