DOTA 2 requires a lot of reading in addition to figuring out mechanics to become fun. I guess similar applies to LeL.
Main difference between League and doto are following:
-doto heroes have 3 primary attributes: STR, AGI, INT. Every hero has specific stat gain, and 1 main stat. The main stat is the one his right-clicks get damage from, but flat damage items exist.
-doto has way stronger CC than league, and a lot of items have strong CC too, in comparison to league. It's why people prefer dota over league: mistakes are punished more
There's also a lot more heroes with actual micro, and there's a lot of small details that make or break your builds, like Orb Effects, the fact that Illusions and illusion heroes don't benefit from flat damage, turn rates (*input lag*), different damage types (that got simplified with the last patch) etc.
Basically, read up a lot on the game, build appropriately, and you win.http://www.purgegamers.com/welcome-to-dota-you-suck#.VCbO0FdJa70
Read this too, has a decent amount of small stuff.
Also, try reading up on a lot of heroes or try seeing them in action, how they work, either in games or vids.