Model casting calls is similar to an actors audition for a role. I have broken his question to separate them. 

Moises:  Normally I like to know what is the agency looking for in a model before I attend a casting so I can prepare. However never truly get to know what are they looking for. How can I know what are they looking for in a male model ? Vikrant: When it comes to casting and what the agencies are looking for in a model, I would say always dress to impress but never over do it. Typically a good pair jeans and nice black tees with jacket would work good. I would also recommend to wear shoes with some heals in stead of just sneakers. At the end of the day you get few minutes to make an impresion and the saying first impression is the last impression works very well in casting situation. I would never get disappointed if you are not selected for the project because the reason you are not selected is because most likely you did not fit the character description they are looking for.  There is nothing personal about it. Moises: What are always to know in what direction to go before hand ? Like; what should I be wearing, is there a certain height and weight, do they want someone athletic built or slim ? These are thoughts and questions that I would love to know ahead of time so I can better prepare.Vikrant: First portion of this question I believe I have answered above. You have to be prepared professionally that means you should have a good portfolio book with awesome pictures a comp card, look your best,  As a male model if you are below 6 feet of height then you typically would focus on commercial modeling and acting. For that you can be of any shape size or age. 

Moises: I remember attending an open casting call for a agency several years back. I was confident I would get in with the agency. I had everything I needed my portfolio, comp cards and business card. They were even nice and friendly. I felt I did good. I never got a call back and it depressed me for a little while but I still continue to try and persue what I like to do.

Vikrant: Casting calls are not personal, when the agency is doing a casting call clients are typically present and  there is a concept and story board which require certain type of looks to play that role. You will be preselected based on your pictures and they want to see you in person and then make there final decision. I hope these answers will help you and answer your questions. Thank you