One of the most important functionality which we do in our day to day work is Vendor Management,or should I say how to do it effectively. Here are a few tips which I would recommend and if needed you can add as well:
1.Always do a thorough check of the Vendor project's, background,or have cross reference check through a reliable source before assigning a project.
2.Always have a view point of the established setup in mind and strongly convey the same feeling to the Vendor, rather than he imposing a particular product/solution to you.Make you feeling loud and clear.
3.Always check on the support which the Vendor is willing to offer, mostly in critical situations of crisis. He will be your only wall of support. The more stronger it is more reliable you will feel.
4.Always have a cost effective solution provided by the vendor,no compromise on quality or support but aim for better ROI.
5.The older the relationship better they work in your favor, the more reliable and secure in your dealing and communications you will feel.
6.Always provide a better picture of your environment to the vendor for good decision making, given him time to settle before you feel you are confident with him.
Remember it is "Marriage on Earth" and there are always two parts of the coin. Choose wisely and clearly rather than regret later.