1. Fast
The Prophet (S) recommends that we fast on this day: “It (fasting on the Day of Arafah) expiates the sins of the past year and the coming year.” [Muslim]
It goes without saying – if you are unable to fast, Allah (S) knows your circumstances and He is the most just and merciful. Do not fret, you can still take part in all other aspects of worship inshallah.
2. Repent
If there is one theme for this day, it is forgiveness. Allah (S) forgives those who seek Him and sincerely repent on this day – and if you are fasting, don’t forget that your sins will inshallah be expiated for the previous AND coming year.
3. Make Dua
This is the tiiiiime for dua, sis. The Prophet (S) said of this day: “In it, there is an hour in which no believing worshipper makes a supplication to Allah for good, except that Allah answers it for him, and he does not seek Allah’s protection from evil, except that He protects him from it.” [Tirmidhi]
Ask Allah (S) for anything and everything you can ever want, both for this life and the next. Remember, no matter how difficult you think your asks might be, your problems are not, and will never be, bigger than your Lord, so don’t hold back in your duas. Ask for the biggest and the best and the boldest of your dreams – and make dua for others as well. Keep your parents, your loved ones, and the greater ummah in your prayers.
4. Remember Allah (S) through Thikr
This is a great way to worship when you can’t escape from life’s responsibilities. While you work, make thikr. The Prophet (S) said, “During [the 10 days of Thul Hijjah] recite a great deal of tahleel, takbeer, and tahmeed.” This means to say La ilaha illa Allah, Allahu Akbar, and Alhamdulillah.
Another one recommended to say on this day is:
لاَ إِلَهَ إِلاَّ اللَّهُ وَحْدَهُ لاَ شَرِيكَ لَهُ، لَهُ الْمُلْكُ، وَلَهُ الْحَمْدُ، وَهُوَ عَلَى كُلِّ شَىْءٍ قَدِيرٌ
La ilaha illa Allah, wahdahu la shareeka lah, lahu al-mulk wa lahu alhamd, wa huwa ‘ala kulli shay’in qadeer
"There is no god but Allah, the One, having no partner with Him. Sovereignty belongs to Him and all the praise is due to Him, and He is Potent over everything."