It's been nearly two years since I started working part time in a needlepoint shop.
I thought I would share some of my thoughts and advice. Not all of this is originates with me.
My number # 1 piece of advice to needlepointers, but it can apply to other needleworkers: don't toss the thread label or write down that information. Every week I see someone in a panic because they are running out of thread and they don't know what it is. After a while you get good at playing detective, but it can be difficult especially with older pieces. Of course, purchasing enough thread to begin with is a terrific idea, but sometimes it's an educated guess. Or sometimes things have been ripped and restitched and you just run out. Knowing dye lot numbers is also crucial on threads that have them. Color can change, sometimes drastically, from one dye lot to another.
I've had this particular problem myself with an ornament kit and lucky for me, my boss knew what the thread was. This was back a few years when I was lacking in needlepoint experience. Right off I found two of the three colors I needed. Took me longer to locate that third color - nearly two years. Funny how I never thought about ripping out and starting again with a new color which is always the option of last resort for some of us.