The first step in this process is developing an awareness of the Alveolar Tap sound. This means discovering where it occurs in the mouth as well as the manner of articulation.
Let’s start by taking the English consonants /d/ /t/ and /n/. Take your tongue and make each of these sounds and note where you put the tip of your tongue (it’s the alveolar ridge). The Alveolar R sound is made at this exact spot, too (hence the term Alveolar Tap).
There is one major difference between the /d/ and /l/ sounds and the Alveolar R sound: length.
For /d/ /l/ and /n/, there is a certain amount of time required to make the sound. If you create a /d/ /l/ or /n/ movement in less than that time, you are effectively making an Alveolar Tap.
In other words, making the /d/ /t/ or /l/ sounds really fast and you will create a tap sound.
To show you, repeat after me in the audio below. Eventually, your tongue will be moving so fast that the consonant will evolve into an alveolar tap /&/.