Different methods depending on the situation and word. One that often works is the hum/uh method were instead of starting the difficult word, I'll start with 'uh..' and immediately put the word in as part of the 'uh' or 'hum' sound. So, instead of getting stuck on 'Water', I'll say 'uh-water' with the 'uh' very quiet. Fun fact: this is how Winston Churchill managed to be a public speaker despite his stutter - if you listen carefully to his old speeches, you can hear an almost imperceptible 'hmm' sound he adds to the start of many words.