The only real way to get ahead of the curb is to stay up to date with Shounen Jump in Japan and other big name tankobans on what they're releasing. Series that end up becoming a cover art, or have a color spread inside the book, are ones you want to keep your eye on - aka One Piece, Soul Eater, and so forth. It's hard to predict what will become "big" enough to warrant an anime, which will automatically shoot something's popularity. But look at Saiyuki - hasn't had an anime update in years and yet the manga is still going strong due to a dedicated fanbase from both Japan and the world. Which is where you get into finding the mangaka, artist, writer, on Twitter and follow them there. Like the mangaka for Hidoku Shinaide posts updates for some things on their twitter, including images and prep for the art book they did last year.
But of course, it's all in Japanese, and auto-translate might be fussy, and even finding who to follow can be a pain. If I recall right though, Shounen Jump, and a few other tankobans, have websites where they post SMALL snippets about what they're going to be releasing or what they just released. I think Famitsu is another. Some are dedicated to just one series though, like the "Tales of" tankoban is a magazine dedicated solely to Tales of products and advertising.
An english alternative would be to stalk tumblr. Attack on Titan was huge on tumblr when it was being released in Japan, before there was even an annoucement for the anime to be picked up in english. Lots of the "current" at the time tags for it were "snk", an abbreviation of the Japanese title. And lots of fans who were there from the start, don't want to use the "aot" tag. Just food for thought.
