Each time I water my potted plant, I notice that the surface of the soil is holding water. Should I loosen it up with a small spade? Once I have loosen up the soil, is there anything else I should do?
If water goes down in sometime then you don't need to do anything. Water moves slowly inside.
Else you can read below:
Water gets accumulated above the soil when the soil is more concentrated with clay, in a mix of sand, silt & clay. You can loosen up the soil and add some silt and sand, so that they improves water drainage.
Also do not forcefully fill your pot with the soil, just fill loosely, otherwise soil will be compacted leaving no space for water to move downwards.
Detailed reference to estimate your soil type: http://www.ext.colostate.edu/mg/Gardennotes/214.html
Its possible the soil is lacking sufficient calcium. See http://www.sierravistagrowers.net/growild/sites/default/files/Soil%20flocculation.pdf