Rollerblading good desicion, you want to be orginal unlike skateboard because everyone does it.
How come most skateboards dont even know how to do 1 trick?
Anyways my best advice to you is first get the correct pair of skates (Aggressive Inline Skates) so you can do stuff like grinding. I recommend either: Razors
http://www.razor-skate.com , USD
http://www.usd-skate.com , or Remedzy , even Rollerblade TRS are a good beginner skate.
Second try rolling up to a skate park and learn how to drop in. Dropping in is when you go down a ramp (half pipe, 1/2 pipe, ect)
Remember when you try this LEAN FORWARD this is very important unless you enjoy falling striaght on your *** from the top of the ramp.
Third PRACTICE nothing comes over night, "yea yea but rollerblading looks so easy i could do that". Ah ha ha very wrong it takes time. Even though one may be able to progress in rollin a lil faster than skateboarding, keep in mind that the sh*t pro Rollerbladers do (look up Julihan Bah, Brian Shima) is 10 times more balls out than the sh*t pro skateboards do and is 10 times more dangerous. But its the best sh*t out there man.