Publisher viewpoint here.
Editing is a huge hurdle, both for the publisher to get the editing done and correctly done in a timely manner, also sometimes not being over-ruled by the client. Marketing can be a hurdle, as marketing is much more than simply getting a book into a store.
The marketer should also think of the 'branding' of the client. Making the clients 'name' something that standing alone attracts individuals.
Part of marketing, and branding is book reviews. To be critically looked at, and then critiqued is something that is vital to getting sales. When one reads about various run-away authors that were 'discovered' one always hears about the book being read by the right individual. These three things are key in our opinion.
If anyone needs a book cover design I can help! But to answer the question I would say time and money to promote is a big challenge when DIY. Also finding the right places to promote that will be most effective in creating sales is a challenge. If I could get someone to do this for me for free life would be so much better lol!
There is always the high school or nearby college where the art students love a challenge. One of my best covers ever was developed by a college student. It is nice to throw a pizza party for the class when it is finished. Most classes have a license countywide for a very expensive art program and most art teacher are always willing to get a little recognition from coaching the students. You also have an agreement that you may or may not use what is created, but usually, it is as good as anything you can get anywhere.
Before ever agreeing to have someone do a cover ask for a portfolio, and ensure that they have done many many covers. There is an art to a Book cover. There is also a psychology of knowing what the potential buyer is thinking and what attracts them. Take a look at a few in our portfolio. http://800publishing.com/portfolio/group/1/
Both of these books shine a light on the early days of these two authors and the paths they took to get to where they are today. And there are a lot of surprises.
Dan Brown, believe it or not, started out as a singer/songwriter in the early 90s and actually released a CD called "Angels & Demons", the same title as that of the book which became a huge bestseller and a movie following his success with The DaVinci Code. But none of this came easily. Editors, agents and publishers can sometimes seem more like obstacles in the way of success than one might assume. "The Man Behind The DaVinci Code" is a fascinating look into the reality behind the rise of an obscure writer into the spotlight of bestsellerdom.
Stephen King's "On Writing" is a must read for everyone who aspires to become an author or who is already well into the process of working toward that goal. Reading "On Writing" is like having the master, Mr. King, right there sitting next to you as you share some coffee and he tells you all the ups and downs of his career from the very beginning. And then he shares with you a lot practical advice on writing; advice based on his years of experience as an author. It's written in a warm, conversational tone, easy to read and ultimately very impressive.
Used copies of these two books can be found for about $3.00 or less at amazon.com. A little bit of money for some entertaining reading and insightful information.