summoning skill is very hard to raise up...
the first 200/250 points you can easily skill up only summoning avatars and release them...
after that, you have to spam BP's ... is the only way... so the person who posted above is right : join some abyssea pt's, take off all the "summoning skill +" gear you have and start to spam BP's every 30 seconds, rage and ward, maybe rage magical BP have a better chance to skillup then physical rage BP's... or, you can join every shout of Boss or NM fights, because you can skill A LOT if you spam BP over an high level NM or Boss... try and you'll see... good luck!