My friend (the Prophet ﷺ ) advised me to observe three things: (1) to fast three days a month; (2) to pray two rakʿat of Duha prayer (forenoon prayer); and (3) to pray witr before sleeping. (Using translation from Bukhārī 1981)   

أَوْصَانِي خَلِيلِي أَبُو الْقَاسِمِ ﷺ بِثَلَاثٍ «صَوْمِ ثَلَاثَةِ أَيَّامٍ مِنْ كُلِّ شَهْرٍ وَالْوِتْرِ قَبْلَ النَّوْمِ وَرَكْعَتَيِ الضُّحَى»