Ignoring the Decade discussion, since that will take you going around in more circles than a farmer investigating his freshly extraterrestrial violated crops, I can only throw one bit of advice on where to go from Decade:
Yes, in a way you should forget everything you know in terms of story, or at least remember that Decade was in fact different stories and characters from the main serieses. HOWEVER, I would highly suggest looking back over it and remembering which worlds you liked seeing.
Sure, Ryuki world was completely different in it's original series, as there was no trial system, Reiko was a reporter, and we missed out on the world's second greatest boss outside of Mr. Kougami/Cakeboss. (seriously, if Ore Journal was hiring, I suspect I'd be fired for not being able to keep a straight face at the Editor-in Chief's antics)
But the idea of 13 Riders is there. The Last Man Standing concept is there. Shinji trying to do the right thing while everyone else has their own agenda is there.
Think about what worlds grabbed you, and what about them grabbed you, and I think you can safely go from there. As long as you remember that Decade is AU, I still think it's an excellent series to 'dip your feet' into other Rider worlds so you can see what they're all about and what they might come to and decide what to watch next. I tend to think it's slightly more reliable than watching the first two or three episodes in a series, since oftentimes it takes two to three episodes to set up the story in full.
Bottom line: just give the worlds that you found interesting in Decade a shot. Just remember that they're AU, so you'll likely be lost on story. But if it pulled you and you liked it, I think you've still got a good chance of enjoying the main series.
Yes, in a way you should forget everything you know in terms of story, or at least remember that Decade was in fact different stories and characters from the main serieses. HOWEVER, I would highly suggest looking back over it and remembering which worlds you liked seeing.
Sure, Ryuki world was completely different in it's original series, as there was no trial system, Reiko was a reporter, and we missed out on the world's second greatest boss outside of Mr. Kougami/Cakeboss. (seriously, if Ore Journal was hiring, I suspect I'd be fired for not being able to keep a straight face at the Editor-in Chief's antics)
But the idea of 13 Riders is there. The Last Man Standing concept is there. Shinji trying to do the right thing while everyone else has their own agenda is there.
Think about what worlds grabbed you, and what about them grabbed you, and I think you can safely go from there. As long as you remember that Decade is AU, I still think it's an excellent series to 'dip your feet' into other Rider worlds so you can see what they're all about and what they might come to and decide what to watch next. I tend to think it's slightly more reliable than watching the first two or three episodes in a series, since oftentimes it takes two to three episodes to set up the story in full.
Bottom line: just give the worlds that you found interesting in Decade a shot. Just remember that they're AU, so you'll likely be lost on story. But if it pulled you and you liked it, I think you've still got a good chance of enjoying the main series.