Judging from your posts, I suspect that your answer to what the best way is is production. That is conversations whether spoken or online discussion threads http://discourse.textkit.com/t/topic/11961/1 or writing stories. To work either you need someone who knows Greek very well to help you or what you produce needs to be trying out what you have read in a grammar book. At least it has to be that way for me. Hence my optative practice story http://discourse.textkit.com/t/bad-neighbor-optative-practice/12834/1 was based on the relevant section of one of Taylor’s books. Even then it is thanks to the help from mwh that that story is in reasonable Greek.
So if you don’t have access to a Christofe Rico there is no escaping grammar books even if to learn effectively use them you need to invent more active ways of using them than they envisage.