无意中看到了这个老外的建议，觉得对我们这些做外贸的朋友来说很实用，所以贴在这里跟大家一起分享！

As a sourcing agent and buyer I can tell you what is a good quotation for me:it includes all relevant information ! My job is to find a reliable supplier at a reasonable price in the shortest time possible.
It is very possible that I will choose a supplier whose price is a few percent higher but the quotation is complete. That means, it includes: - FOB (!!!) price, with seaport marked! (I often get FOB quotes without location. Obviously for me in Europe a FOB Shanghai price is higher than a FOB Xiamen price, since shipping rates are different).
- delivery time (so far no Chinese supplier was able to keep the promised delivery time for my projects - 90% delay, 10% early)
- package unit (carton details)!!! Carton weight, size, volume, content, material. It is very important!!! Usually this point is simply left out by suppliers. But I - and most full-time buyers - have just simply no time to beg for any details separately!!! If a quotation misses this, I simply delete it. I have no time to ask for these points, but I can only calculate my shipping cost with this info!!!
- payment conditions must be exactly discussed.
I hope suppliers will consider these points in the future. If you include all relevant information, you can really help your partner in his decision. And for the supplier, it is a job done once, you needn"t work out each detail separately.