I wouldn't call myself a big youtuber, but I'd say I had some success
For me, my first 'big' video, I spent about 150 hours on one video, and I've noticed the more time and effort spent on something, to make something as perfect and as brilliant as you can will reep the rewards in the end... and tbh I only shared the video tothe usual FB, Twitter, Tumblr, and a couple other sites, it spread on it's own
But what you saying about spamming, well the best way, and I do it all the time is to get involved in the YouTube community
Watch + comment on other peoples content, not just popular content, maybe YouTubers who are just starting out soon, yeah of course not all will even reply, some will reply, and then some may even check out your channel, watch some videos, and stick around
.
Because that's what you want isnt it, for people to watch yours, comment and even sub. Well to get that, you need to give in return
Also sharing on your Facebooks, twitter, Tumblr and even creating a blog will all help. It's not easy and takes a lot of hard work, but the more work and effort you put in the more you will get out of it
[DOUBLEPOST=1346336519,1346336503][/DOUBLEPOST]Hope that helps a wee bit! it has done for me