Practice technique for pronouncing /p/ :

Take a deep breath. Bring you lips together for /p/ and hold your breath.  When you can't hold your breath any longer, open your lips and let the air out. You will hear a big puff of air. Now you know the sound of /p/.  Do it without holding your breath and it will sound natural. The consonant /p/ in word-initial position and at the beginning of stressed syllables in word-medial position is voiceless and aspirated;  you can clearly hear the puff of air as the lips close and then open.

Practice these examples of voiceless, aspirated /p/:     

pain, peace, pile, pose, pool, pat, peck, pit, pot, pun, put, pause, point Play Video 
repair, repeat, compete, compare,  compile, appear, apparent, appoint

The consonant /p/ is not aspirated in medial position when the syllable beginning with /p/ is unstressed.  Pronounce these words:  

simple, supper, super, copper, coping,  tapping,  rapid, ripen, happen  Play Video 

The consonant /p/ is voiceless and unaspirated in final position, but it must be formed for the word to sound correct.  Pronounce these words:

soup, soap, tape, type, hoop, leap, steep, stop, step, stoop, keep, sip, lip

The consonant /b/ is also pronounced by pressing the lips together and opening the mouth quickly. It is voiced in initial, medial, and final positions.  Practice:

bake, beans, bike, boat, boost, bat, bed, bill, box, bun, boy, ball, book  Play Video 
rubber, tubing, stubborn, robber, rabid, cabin, hobble, lobby, maybe
cab, rub, rob, tube, lab, stab, cube, rib, crib, fib, lube, throb, grub, knob  Play Video