Please advice bus option from Hong Kong airport, i need to go to Shim Tsa Shui next week

Oh, you must refer to Tsim Sha Tsui.
You can take airport shuttle bue no. A21 to Cameron Road, Nathan Road. The ticket fare is 33 HKD.
There is the other cheaper way, but you need to transfer the buses. You can take bus no.E21 to Sai Yeung Choi Street South. Then transfer to bus no. 2 at Mong Kok Railway Station, and get off at Cameron Road. After arriving, walk to Tsim Sha Tsui. The ticket fare is 18.9 HKD.

If you want to go Central Station, you can take bus no.E11 to Jardine House, Connaught Road Central. The fare is 21 HKD.
If you want to go Kowloon Station, take no. E11 to Western Harbour Crossing Toll Plaza. The fare is 21 HKD.