अनुस्वार - 1

In संस्कृत, अनुस्वार( ं) represents a nasal sound (consonant). The nasal sound is pronounced according to the nasal consonant belonging to the class of the consonant that follows.
Key to pronunciation:

1.  ं+Guttural  = ङ्+Guttural
2.  ं+Palatal  = ञ्+Palatal 
3.  ं+Lingual/Cerebral = ण्+Lingual/Cerebral
4.  ं+Dental  = न्+Dental
5.  ं+Labial = म्+Labial
6.  ं+Vowel = म्+Vowel

If a semivowel follows  ं ,  ं is pronounced as म्. Some, however, pronounce  ं by nasalizing the semivowel (य्, ल्, व्).

Note: This post is only for pronunciation of  ं, not writing. For writing, refer to अनुस्वार - 2.