Stuff which might help.. 1. I know C/K is formed by your articulators (what happens in your mouth), but try to get the sound of C + whatever vowel follows into your chest, so that you can feel the vibrations, if you were to put your hand there. 2. Practise 'hit and hold' on the C. Prolong the sound on PURPOSE. For example 'cccccccccccccccccccancel'. Again, think about taking tension away from your articulators/mouth, and into your chest. (yes, I'm Mcguire!)