I own Crossword Compiler 7.0 Professional bundle, so I'm not sure how the individual components break down, but I'm quite satisfied with it. (I guess they're up to verson 8.0 by now). (The "professional" version allows you to rerank wordlists right at the filling menu ... and that's a really nice feature).
Once you get the software, you'll want to get a better wordlist. If you pay to join the Cruciverb-L mail list on this website, you'll have access to a wordlist containing all the entries that have appeared in major crossword puzzles (NYT, etc) for the past 20 or so years. That is a much better wordlist to use than anything available in any software, but unfortunately all the words are equally ranked, so it could be a nightmare to sort through the word list menus which pop up while you are filling a grid. Given that, I think what many constructors do is request a mentor via the Cruciverb-L mail list, and after a few sessions a mentor will supply a good rudimentary wordlist which is somewhat decently ranked. This seems to be the best general source.
One other useful resource to acquire from the Cruciverb membership is the Ginsberg clue database ... which can be downloaded for free.
The software, the wordlist and the clue wordlist are three major things you'll get a lot of mileage out of.