The grave of the pious believer is a part of Paradise. Read in Quran how the believers are best received by the angles when they die. (Those pious believers whose souls are taken by the angles, saying to them: Peace be upon you) (Sura 16, Verse 32).
Also you can read in in Sura Al-Waqi'a how the believers get peace and happiness when they die. (Sura 56, verse 90.)
Doing good deeds will make your grave a part of Paradise especially fulfilling your obligatory Prayers on time, paying charity,v helping people who are in need, performing Night Prayers, Ziyarat Ashura, remembering Allah and reciting Quran, etc.
No fear on the obedient servants of Allah (SWT) as we read in Quran ( Those who say: Our Lord is Allah and remained straight and pious, on them shall be no fear, nor shall they grieve) Sura 46, verse 13.
Death of the believer is the best moment is his life because he will transferred from life of challenges to a life of mercy of Allah (SWT).
Keep reciting ALLAHUMMA SALLI 'ALA MUHAMMAD WA AALI MUHAMMAD. اللهم صل على محمد وال محمد
as many times as you can. It will enlighten your life and your grave.
'Keep on reciting ASTAGHFIRULLAH RABBI WA ATOOBU ELAYH,أستغفر الله ربي وأتوب إليه
as it purify us and cleans us from sinful acts.
Have great hope in the Mercy of Allah. Surely Allah is The Most Merciful.