The Methodology in Studying Aqeedah (Creed)
The First Stage
Start with the smaller books of this discipline:
"The Four Principles" (Al-Qawa'id al-Arba')
"The Three Foundations" (Al-Usul al-Thalathah)
"Unveiling the Doubts" (Kashf al-Shubuhat)
"Matters of the Pre-Islamic Period of Ignorance" (Masa'il al-Jahiliyyah)
"The Six Foundations" (Al-Usul al-Sittah)
"The Book of Tawhid" (Kitab al-Tawhid)
...all by Shaykh Muhammad ibn 'Abd al-Wahhab, may Allah have mercy on him.
Then, one should take a portion from the books on Iman, such as:
"Al-Iman" by Ibn Abi Shaybah, may Allah have mercy on him
"Al-Iman" by Abu 'Ubayd al-Qasim ibn Salam, may Allah have mercy on him
...and complete the trio with the book of the Qadi Abu Ya'la al-Hanbali, may Allah have mercy on him.
Then, one studies the books:
"Nullifiers of Islam" (Nawaqid al-Islam) by Ibn 'Abd al-Wahhab
"Proofs Regarding the Allegiance of the Apostates" (Al-Dala'il fi Mawalat al-Murtaddin) by Sulayman ibn 'Abdullah
"The Path of Salvation and Liberation from the Allegiance of the Apostates and the Turks" (Sabil al-Najah wal-Fikak...) by Hamad ibn 'Atiq
"Beneficial Words Regarding the Occurring Disbeliefs" (al-Kalimat al-Nafi'ah...) by Sulayman ibn 'Abdullah
...and other similar works.
The Second Stage
Study the books of the Sunnah from the Salaf:
"Al-Sunnah" by Harb ibn Isma'il al-Karmani
"Al-Sunnah" by Abu 'Abdullah Muhammad ibn Nasr al-Marwazi
"Al-Sunnah" by Abu Bakr al-Khallal
"Al-Sunnah" by 'Abdullah ibn Ahmad
"Al-Sunnah" by Abu Bakr ibn Abi 'Asim
"Refutation of the Jahmiyyah" (al-Radd 'ala al-Jahmiyyah) by Abu Sa'id al-Darimi
The Third Stage
One studies these foundational works:
"Sharh Usul I'tiqad Ahl al-Sunnah wal-Jama'ah" by Abu al-Qasim al-Lalika'i
"Al-Shari'ah" by al-Ajuri
"Al-Ibanah al-Kubra" by Ibn Batta al-'Ukbri
...and alongside them, one studies:
"Al-Iman al-Kabir" and "Al-Iman al-Awsat" (Sharh Hadith Jibril), both by Ibn Taymiyyah, may Allah have mercy on him.
The Fourth Stage
Study these books and topics:
"Al-Iman 'inda al-Salaf wa 'Alaqatuhu bil-'Amal wa Kashf Shubuhat al-Mu'asirin" by Muhammad ibn Mahmud Al Khudayr.
Then one reads on the topic of Qadar (Divine Decree):
"Al-Qada' wal-Qadar fi Daw' al-Kitab wal-Sunnah wa Madhahib al-Nas fihi" by Dr. 'Abd al-Rahman ibn Salih al-Mahmoud.
"Shifa' al-'Alil fi Masa'il al-Qada' wal-Qadar wal-Hikmah wal-Ta'lil" by Imam Ibn al-Qayyim.
The Fifth Stage
One studies on the topic of the Names and Attributes of Allah from these books and their like:
"Al-Tawhid" by Ibn Khuzaymah
"Al-Tawhid" by Ibn Mandah
"Naqd 'Uthman ibn Sa'id al-Darimi 'ala Bishr al-Marisi"
"'Aqidat Ashab al-Hadith" by Abu 'Uthman al-Sabuni
"Al-Wasitiyyah" by Ibn Taymiyyah and its commentaries
"Al-Fatawa al-Hamawiyyah"
"Al-Tadmuriyyah" and its commentaries
"Al-Qawa'id al-Muthla" and its explanation by Ibn 'Uthaymin.
("Al-Manhaj fi Talab al-'Ilm bi al-Tadarraj" p. 1 by Shaykh Hassan Hussein, may Allah preserve him)