The following is advice for business people/shop workers etc but I'm sure others can take something from it too.

We are living in a world of means. Working hard and exerting oneself is a means of extra income. During this festive economic season, commence business early in the morning. The Prophet said,

"اللَّهُمَّ بَارِكْ لِأُمَّتِي فِي بُكُورِهَا"
“O Allah, bless my ummah in their early hours of the day.” (Sunan Tirmidhi)

The early hours are submerged in blessings. It will be noticed that the amount of work carried out in this time is more in comparison to any other time of the day.

Whenever the Prophet exported or imported goods, he would send the caravan in the morning. The sahabah state that these caravans would return with a high profit margin. (Sunan Tirmidhi)

In the festive period of Christmas, majority of the shoppers are Christians. They are out looking for bargains and sales in order to buy gifts for their loved ones.
A Muslim should hunt for opportunities to convey the message of Islam. This Christmas shopping spree presents Muslim businessmen a golden opportunity to manifest the true nature and spirit of Islam.
We need to adopt a gentle and courteous disposition in these days all the more. Whoever enters our stores, they come seeking the dunya. Let it be that when they exit your shop, they are impressed with the sublime character of Islam and Muslims.
Do not confront any Christian regarding beliefs around Christianity. This is not the time. Any discussion against Christianity at this time will be counter-productive. Rather, impress them with your akhlaaq.
Allah (swt) says,
ادْعُ إِلَى سَبِيلِ رَبِّكَ بِالْحِكْمَةِ وَالْمَوْعِظَةِ الْحَسَنَةِ وَجَادِلْهُمْ بِالَّتِي هِيَ أَحْسَنُ(النحل:125)
Invite to the way of your Lord with wisdom and good instruction, and argue with them in a way that is best.