Your marketing career is only as good as the resources you have at your fingertips. I can’t overstate the benefit of regularly reading case studies and opinions from the industry.
Many times clients and friends have come to me for advice and I’ve been able to say ‘I remember x company did what you want to do. This is what they did and this is how you could do it better.’
This is a page of marketing resources that I use and recommend, though (with the exception of the IDM where I studied,) I have no affiliation with any organisations mentioned.