Then, are there any principles for using the strength perspective in practice?

Not at all.

I see. Thank you so much!

The strengths perspective holds six principles, including:
1) the initial focus of the helping process is on the strengths, interests, abilities, Knowledge, and capabilities of each person, not on their diagnosis, deficits, symptoms, and weaknesses as defined by another;
2) the helping relationship becomes one of collaboration, mutuality, and partnership;
3) each person is responsible for his or her recovery;
4) all human beings have the inherent capacity to learn, grow, and change;
5) helping activities in naturally occurring settings in the community are encouraged;
6) the entire community is viewed as an oasis of potential resources to enlist on behalf of service participants.