A short description of some consonantal allophones.

One of my students has asked me for help with the description of allophonic variants.
Here I include, for him and any other one who might make good use of it, a short list of Consonantal Allophones descriptions.

ASPIRATION: It is an extra puff of air heard with the release of a plosive before the onset for the following sound. It affects voiceless plosives, initial in a stressed syllable.
When a vowel follows the voiceless plosive, we perceive the puff. When a consonant follows, it is devoiced.

DEVOICING: It is the removing of some voicing from an originally voiced sound. It affects voiced consonants with a voiceless counterpart, when they are preceded or followed by voicelessness (silence or a voiceless sound)

INAUDIBLE RELEASE: The release stage of a plosive is not heard. It affects all plosives when they are followed by an oral stop (a plosive /p/, /b/, /t/, /d/, /k/ and /g/ or an affricate  /tʃ/ and /dʒ/)

NASAL RELEASE: The release stage of a plosive is produced through the nose. It affects all  plosives when they are followed by a nasal sound. In order to produce it, we lower the soft palate.

LATERAL RELEASE: The release stage of the plosive is produce through the sides of the tongue. We lower the sides of the tongue to produce it. It affects alveolar plosives /t/ and /d/ when they are followed by the alveolar lateral /l/.

SYLLABIC VALUE OF CONSONANTS: A consonant takes on the value of syllabic nucleus. It affects the nasal sounds /m/, /n/ and /ŋ/, the alveolar lateral /l/ and occasionally the post-alveolar approximant /r/.
The /ə/ is elided between two consonants, so the second consonant becomes longer to take up the time of a full syllable.

DENTAL ASSIMILATION: It is an instance of assimilation of place. It affects the alveolar plosives /t/ and /d/ , the alveolar lateral /l/ and the alveolar nasal /n/ under the influence of a following dental fricative /ð/ and /θ/. The tip of the tongue does not articulate with the teeth-ridge but with the upper teeth.

POST-ALVEOLAR ASSIMILATION: It is an instance of assimilation of place. It affects the alveolar plosives /t/ and /d/ when they are followed by the post-alveolar sound /r/. The tip of the tongue does not touch the teeth-ridge but a part a little backwards from it. At the same time, the post-alveolar turns into a fricative [ɹ] .

LABIO-DENTAL ASSIMILATION: It is an instance of assimilation of place. It affects the bilabial and alveolar nasals /m/ and /n/ when they are followed by the labio-dental fricatives /f/ and /v/. The articulation of the nasal is produced between the upper teeth and the lower lip.

LABIALISATION: A consonant is produced with noticeable lip rounding. It affects any consonant occurring before the labial-velar approximant /w/ in the same syllable. The lips are rounded anticipating the rounding of the /w/.

Hope it helps!