Listen to the Lord, He'll tell you. I know that sounds very simplistic but it's really the best answer. :-)
Here are requirements (Isaiah 58):
No, this is the kind of fasting I want:
Free those who are wrongly imprisoned;
lighten the burden of those who work for you.
Let the oppressed go free,
and remove the chains that bind people.
Share your food with the hungry,
and give shelter to the homeless.
Give clothes to those who need them,
and do not hide from relatives who need your help.
Then your salvation will come like the dawn,
and your wounds will quickly heal.
Your godliness will lead you forward,
and the glory of the Lord will protect you from behind.
Then when you call, the Lord will answer.
Yes, I am here, he will quickly reply.
Remove the heavy yoke of oppression.
Stop pointing your finger and spreading vicious rumors!
Feed the hungry,
and help those in trouble.
Then your light will shine out from the darkness,
and the darkness around you will be as bright as noon.
The Lord will guide you continually,
giving you water when you are dry
and restoring your strength.
You will be like a well-watered garden,
like an ever-flowing spring.
Some of you will rebuild the deserted ruins of your cities.
Then you will be known as a rebuilder of walls
and a restorer of homes.
Keep the Sabbath day holy.
Dont pursue your own interests on that day,
but enjoy the Sabbath
and speak of it with delight as the Lords holy day.
Honor the Sabbath in everything you do on that day,
and dont follow your own desires or talk idly.
Then the Lord will be your delight.
I will give you great honor
and satisfy you with the inheritance I promised to your ancestor Jacob.
I, the Lord, have spoken!
And of course the most important thing Matthew 6:16-18:
When you fast, do not look somber as the hypocrites do, for they disfigure their faces to show others they are fasting. Truly I tell you, they have received their reward in full. But when you fast, put oil on your head and wash your face, so that it will not be obvious to others that you are fasting, but only to your Father, who is unseen; and your Father, who sees what is done in secret, will reward you."
I'm excited for you, fasting is a real blessing! We can draw so near to the Lord and feel His wonderful presence however, during these times of getting close we become more aware of our own sinfulness. DON'T GIVE UP THIS IS FROM THE LORD, every time someone saw the Lord in the Bible, they were aware of their sin, and the Lord cleansed them (Daniel, Ezekiel, Moses, Isaiah, Jeremiah).
You can do this my sister!