Tough part: Ser vs. Estar
Easy to learn how to use Ser (with the acronym DOCTOR) and Estar (with the acronym PLACE).
DOCTOR stands for Description, Occupation, Characteristic, Time, Origin, and Relationship.
PLACE stands for Position, Location, Action, Condition, and Emotion.
More detail and examples you can find in the link below. Link: http://www.spanishdict.com/answers/100040/ser-vs.-estar#.VPhk8fyUdyA
P.S: This website spanishdict.com is great!!!
Five years from now, I will still be using the advice you shared today. Mil gracias!
I think that this is very valuable; but I feel that an easier rule of thumb would be to simply ask yourself if what you are talking about is permanent or not? Your name is permanent so you'd use a Ser, your profession is a fairly permanent thing.. again you'd use Ser. Estar on the other hand, no permanent e.g. Estoy bien. You are not always well. But you are right now so it's not permanent. Although if you did say Soy bien you would actually still be understood but it would convey that you are always well or that you are a well person! Is it permanent? That's all I try to remember.
I also would like to point out a curiosity. In some cases you may use either one or the other in a sentence to convey different meanings.
Normally you use "estar" for a temporary state and "ser" to a more deep characterist of your being. For instance:
"Estoy enfermo" - to be sick "Soy enfermo" - to have a chronic illness
"Está callada" - she's quiet. "Es callada" - She doesn't talk much (she's introverted)
"eres un borracho" - you are drunkard "estás borracho" - you are drunk.
Having these two verbs can be funny.