Do you have any contractor tips? The Deck: Part 2

A few blog posts ago, I wrote about a terrible contractor situation with a deck and a careless contractor. I can happily report the deck has been completed - just a month or so behind schedule. My biggest challenge during this whole fiasco was knowing how to deal with the contractor. It was my belief if I spoke up too harshly they would do crap work or take even longer. If I didn't speak up, they may never come back and take their sweet old time.

I would treasure any advice offered about effective ways to deal with contractors who become negligent. I've heard the usual give donuts and coffee - but if the project manager isn't there every day and the workers don't speak English, it seems ineffective to cater to the workers when the real boss is never present. How far can I push a project before I become that nagging client that all contractors complain about - both internally and to other contractors. I won't be taken for a sucker - but I'm also no T-Rex.

Please let me know your thoughts. They're greatly appreciated!