The schwa /ə/ is the most frequent vowel sound in English, so I can understand your concern with wanting to improve your delivery. If you use it appropriately in unstressed syllables, your pronunciation will sound more natural; such as the word
above. Once you master the "a" sound in the word "above" ... substitute it at the end of the words that you have listed; and then terminate the syllabel with an "l" consonant sound. Practicing the schwa sound in the initial position of a word and isolating it in it's own syllable should give you the confidence to then use it in a variety of other placements with more ease.
Here is a good chart that shows where consonant sounds are formed in the mouth (such as the final "l" in your sample list). You can also see on this page that the schwa sound is a problem area for many peoples; so you are not alone.
http://cls.coe.utk.edu/lpm/esltoolki...ntrastive.html