Clipping - NO two animals will ever be clipped the same. You need to picture the PERFECT animal (whether it be a steer, heifer or cow), and then shape them by clipping to make them look more like the ideal. Look at pictures of grand champions from denver, IOS, etc to see things close to the ideal.
Fitting - the best i can say is, watch and learn. You are going to get very little from asking in a forum because you have to see it. I would recommend looking into Kirk Stierwalt's fitting clinics and seeing when he is in your area to attend one. It will be worth every penny you pay.
http://www.kirkstierwalt.com/calendar.html
Tattoos - They are literally a tattoo in the animals ear that is used for identification. It varies as to what is in the ear depending on the breed (recquired for all registered animals), but usually there is a prefix made up of up to 4 letters that identifies the breeder, each breeder will have one, and no one else will have the same prefix within that breed association, and then below, is the animals identification, made up of numbers and a letter. The numbers are usually based on the order of the calves born that year, and the letter is based on the year and is universal across breeds. 2012 is year Z, 2013 is year A, 2014 is year B, etc. The letters I, O, Q and V are not used because they can be mistaken for other numbers or letters I=1, O=0, Q=O, V=U
ex. The breeders Jane and John Doe may have the prefix JJD , have their first calf of the year and designate it 1Z
The tattoo would be
JJD
1Z