Actually, I do not believe there is one. We must learn by being trained by someone that has made mistakes and learned from them. Life experiences are the most useful tools and of course this forum is of great help.
As you learn remember to be careful of what you think you know because before you know it you don't know anything!
Basic Real Estate Appraisal by Richard Betts and Silas Ely - I have the second edition, I think there is an updated version. Part of the California Prentiss-hall Real Estate Series. Very good instructional book. I bought this one on ebay for like $10. Appraising the tough ones is another excellent book - Frank Harrison is the author. A must for rural property/special property. But if you specialize in Rural Property, The Appriasal of Rural Property - 2nd Ed. is a must, available from AI.
Frankly, I cannot think of a better written book than the Basic RE App. of Betts & Ely for laying it out plain and being a big thick easy to read epistle.