I have been given a lot of advice in my lifetime, but when asked to think of the best 3 pieces quite a few popped up in my mind! Obviously relevant to my studies and my future within illustration, not just general life!!
1) SET UP A WEBSITE!..if people can not find you they do not know you exist!! When contacting Art Directors send hand made packs as it is more personal and they are more likely to look at it rather than an email. Choose carefully who you send your work to, make sure your style is relevant otherwise it is a waste of your time.
Also, do not give up!
Garry Parsons gave this advice when I attended a Business Master Class in London run by AOI.
2) Enter as many competitions as possible when you are an aspiring illustrator to get your name out there. And never change your style to suit anyone else.
Olaf Hajek gave me this piece of advice when I visited his studio in Berlin, and it's true you should not be what you think people want you to be or do work you think people want to see, in a fashion they prefer (i.e. digital work)!! but you should just do what feels right for you and keep your own style. Olaf is a very talented painter and he said he will not change what he does to suit other people. I think it's fantastic he has retained traditional methods and he is highly successful.
3) Making mistakes is just as important as doing it right!
My tutor Joanna Nelson gave me this piece of advice today and it is so true, you have to make mistakes to move forward with your work. Be daring and try things, if they work great, if they don't then at least you learn!