There are many important things to consider when buying trading cards like Magic: the Gathering:

• Reasonable Price
• Seller's Reputation
• Ship Time
• Quality Packing

The list goes on, but probably the most important is condition, especially for those who are not just playing, but collecting to make full sets.

As a buyer as well as a seller, I always make sure I am clear on what condition cards I will be receiving are in.  If I am unsure, I ask the seller for an explanation of thier grading scale.  Any seller who truely wants your business, will make an effort to make sure you know what you will be getting.  If you are unsure, just ask!  If you don't get a timely response, you are probably better off finding another seller.

A key thing to consider is that while there is a common system in place, in the end, alot of card ratings come down to opinion.  A great example of this occured last year, while I was working for an eBay drop off store.  We received a large collection of professionally graded baseball cards, some of which were duplicates graded by different companies.  There were some cards that looked identical in condition, but received different gradings from different companies.  The only way I can explain this is that when it came down to it, the grader's opinion, not just knowledge of the standard guideline, effected the score of the card. 

Of course, there are situations where a card is described as Near Mint only to arrive white edge whitening on all sides.  Most will agree, that is not a NM card and in this case, it isn't a matter of opinion, it is a matter of poor grading.  That is why it is important to know if your potential seller is an honest grader.  Check thier feedback, see what their buyers have to say about the condition of the cards they received and of course, ask questions.  And in the cases where you receive a card that does not match the grading it was given, contact the seller and see what they are willing to do.  A good seller, who wants your return business, will do what they can to make the situation right!

A final thing to consider is that the terms some people use do not always match up.  A "Good" condition card may be the equivalent of another seller's "Poor" condition card, while an "Excellent" condition card may be equal to anothers "Very Fine".  For a new buyer, this can get confusing, especially if they are use to certain terms.  I remember when I was learning about book grading and the change in terminology and definitions of each term really through me off, coming from a Collectibles background.  I have found that it is easier to "forget" my own scale when buying cards from others and base my purchases off each seller's individual scale.  Basically, don't assume a seller's "very fine" definition is the same as your own, make sure you know if it is, or what the difference is.  Some sellers only have 4 or 5 different grades on their scale, while others, like myself, have a few more.

If you are a player who doesn't care about condition, then buying should be a breeze, just get the cards with good prices, sold by good sellers!  But for those of you that are like me, who buy cards to add to your collection's complete sets, then the grading of a card is very important and sometimes finding the right card can be a difficult task!

I guess, in the end, I can't stress it enough:  if you are unsure, ASK!  It will save you a lot of trouble in the long run!