What actions should be performed to ensure a good life in Barzakh, God's love, a good ending, that the grave be a garden from the gardens of Paradise, and peace of mind in the grave?

Fear of death and what comes after it is praiseworthy, as long as it does not exceed the limit of pathological fear. Invest this fear in obedience to Allah and hope for His bounty, and strive in righteous deeds, relying on Allah, seeking His help, and frequently supplicating Him; for this is a guarantee of salvation from Allah's wrath and punishment. For more on the causes of a good ending, please refer to Fatwa no. 137196, and Sheikh Omar Al-Ashqar's detailed discussion in "Al-Qiyamah Al-Sughra" (The Minor Resurrection).