One of the biggest questions you'll face as an author is to hire an agent or not. There is no easy way to decide. But the fact is, if you want in a big 5, you have to have an agent. If they want you, they won't contact you, they'll contact an agent of their choice to contact you and then that agent with represent you with them.
What is the job of an agent?
Financially, there are things to determine -
Cost? - Do they really see you as an author or as dollar signs?
Are you just a number to said agent? - How many authors are too many to properly represent?
Will the benefits be worth them? - Would you make as much money with a smaller publisher if you weren't paying agent fees?
Will they be willing to represent you only on the projects you want or do they demand all your manuscripts?
The matter remains that if you are doing some how-to non-fiction, poetry, short stories, journalism or plan from the start to self-publish - you DO NOT need an agent. Most agents won't touch any of this. Not when there's far more money to be made in other stuff.
Themed collections of short stories and many children's books will be a maybe. A well written themed collection, an agent might decide they'd make enough money on. Most children's publishers DEMAND you to have an agent.
The sad fact, is that as authors you write for the love of writing (if not, you're already set to fail). Agents, are different. They work based on determining how much they'll make offer said book. They don't do it simply because they love reading. (If there is such an agent, I'd love to meet them.)
Now many people think you need an agent for any novel, huge how-to concepts, (as mentioned above) children's books and so on. If you have some huge non-fiction novel, based on something that would possibly hit a best-seller list (again, evaluate honestly - we all want best sellers, but in truth, some things are set to be best-sellers while all others aren't).
Before you ever consider an agent, there are several things you must do. If you waste their time, when you are ready, they'll likely pass you by, no matter how great the manuscript it.
*Your brand must already be building. Don't go to them saying you have no idea what pen name you want to write under or that you haven't started anything at all to start promoting said name.
*Have your manuscript done. Don't contact them with an approximate completion date or, worse yet, a concept that you've not even started writing yet. Be ready to be able to submit everything.
*Have said manuscript ready to be looked at. Make sure it's free of grammar and spelling errors. Make sure you don't have missing words, or use he instead of she. Make sure you stay in character attributes (don't change the way they talk or the way they look because you forgot as you wrote the manuscript). Make sure you've called everyone the right name through the whole book (yes, it happens).
*Have a career arc ready for them. Some want them, some don't. But it's better to have it ready instead of telling them you need several days to put one together.
*Be a professional. Tell them what they need to know, but don't over-tell.
*Don't be boastful. If you start telling them how great you are, most agents will toss you in the trash pile. It's their job to determine how good you are.
*Make sure you've investigated your market and you know it. This includes genre and sub-genres.
I hope you've found this helpful and will join me next week for more on agents.