The first thing I tried to summon was a sword. I went to bed knowing I wanted to be able to have a sword. Many nights with no luck. The first thing that worked is alot like what others are saying, a believable reason beyond your current vision. I was fighting and asumed I must have friends fighting near me. I shouted " hey I need a sword, will you hand me one quickly!" then turned to find the friend I asumed should be there. Yep, some guy handed me a sword. Now, it has become much easier, but that was my first success.