How can one attain tranquility simply by remembering Allah as mentioned in the Qur'an 13:28 that says "Verily in the remembrance of Allah do the hearts find rest"?
Though I struggle with some sins, I am overall a practicing Muslim.
Yes, with out any doubt. Real remembering means avoiding sinful acts and keeping our heart and acts with Allah (The Glorious). That will definitely make us attain tranquility.
1. Performing the Prayers on time with dedication and sincere intention is a compulsory act in remembering Allah, with out which no real remembering of Allah (And establish Prayers (Salah) for my remembering) وأقم الصلاة لذكري ( 20:14)
2. Avoiding sinful acts and even sinful thoughts which come from Satan to spoil our tranquility.
3. Reciting or listening to Quran with our hearts not only our ears.
4. Reciting Du'a (supplications) specially what has been narrated from the Prophet (SAWA) and Ahlul Bayt(AS).
5. Performing long Sojood with Du'a or remembering Allah, or Salawaat or Istighfaar. Long Sojood has great effect on our hearts and spirituality and it makes us close to Allah and far from Shaitan. There is a special mention in Quran about Sojood during he night (And from the night, prostrate to Him and glorify Him a long night through (Sura Al-Insaan: 26)
Long Sojood helps a lot in healing and elevation.