I do the sides first and then the top and bottom..
Trick that I have learned - the best way to do the borders are as follows:
For size borders, measure both sides and though the middle - add all 3 measuresments together and divided by 3...that should be the length that you cut for both sides.....
Fold your border in half, put a pin there..then find the center of both halfs - put pins there...
Now do the same with the sides of the quilt - and match up pins - easing in any extra to make both fit....
Follow the same technique for the top and bottom...
It is amazing how well this works....