(Cl)ass, (Cr)ack, (Pl)astic, (Pr)ank For these words I try to pronounce them like Khlass, Khrack , Phlastic or P very low sound and Lastic, Phrank. For initial pronunciation of words starting from P. Exhale and while exhaling from mouth, quickly connect and disconnect your lips to produce P sound. For initial pronunciation of C words....the same logic but do it with your tongue while exhaling..... This is what works for me most of the times. I think exhaling first solved the problem.. And most important...., try to combine the whole sentence into a single word and speak at a constant pace Example: iLovetoPrankChildrenWhoLovePlasticMadeOfChlorine. I hope this helps...this is what I have learnt over my journey. Rock it man. You got this.