@clancam,
It seems a bit obvious but the first thing to do is fill in all the black squares that you can, keeping in mind that the grid is fully symmetrical, not just horizontally or vertically. Then look at the numbers that have been given and check if there is a clue either across or down for that number. If there is, then the square before that will need to be black. That will give you a few more black squares.
Then it's just a matter of filling in the answers, and more black squares as you go. The answers for 1a and 1d will be the same number of letters to keep things symmetrical.
Hope this helps.