Perhaps my testimony is not as in depth as you would like. But I can assure you I did not "just" do what my friend did without much thinking about it. I agonised for weeks over what I should do, if i was saved, whether I was ready to be baptised. I felt that my friend being baptised was my sign. But you're right prayer isn't 100% accurate, I may have misjudged but that does not mean that my action of being baptised was the wrong one, or that my path as a christian now is wrong. I know and believe that Jesus was the son of God and He lived and died for me, I trust in Him as my saviour and choose to lived a life dedicated to him.