If you're serious about publishing and marketing your book, I have a word of advice. Beware. There are genuine people in this world who want to be a part of your success, and there are those who are only out for themselves.
Let's talk about the supportive people first. These may be loved ones, friends, readers or industry professionals. They want you to succeed. Some want it because they know and love you. Some want it because it's good for them. Whether their motives are selfless or selfish, they are on your side. Where you need to be cautious is with their expertise. You may have family and friends who love you dearly and want to give you advice; however, they don't know what they're talking about. I had a well-meaning family member suggest if I wanted to be a success that I needed to start writing what people want to read. He had no clue about the young adult market and how popular it is. So, before you start following anyone's advice -- including mine -- make sure that person has the experience and knowledge to voice their opinions. Otherwise, thank them for their advice and forget what they said.
What about the other type of people? Sometimes it's hard to spot them. I've joined several online writing groups, and if you're serious about writing, I highly suggest that you do, too. Goodreads, Kboards and Absolute Write are great places to get started. On these sites you will meet a lot of knowledgeable, helpful people who will give you the good, bad and ugly about the publishing industry. They share their experience and genuinely hope it helps your career. However, not everyone on those sites is uplifting. I've found myself scrolling through posts and getting discouraged because of their tales of "doom and gloom". I've had to remind myself that I'm completely happy with my journey so far, and while I'm sorry for their bitter disappointments, that isn't my story.
Another type of negative person you might encounter is the one who only wants your money. There are a lot of people in this industry who will promise you fame and fortune if you will pay for their service. Be wary of anyone asking for money. There are legitimate services out there, but it's vital you know what you're paying for and what they can guarantee. I've seen new writers spend thousands of dollars for promotions and review services when they haven't checked out the free stuff first. If you're brand new to the writing game, don't fork over a ton of money you haven't earned yet. Check out the free and cheap stuff (like having your covers designed on Fiverr) and build your reader base. Once you've done that, then spend some of your hard-earned cash on promotions and other services.
This isn't a get-rich-quick endeavor. Don't let people con you out of your money because they say they've discovered the way to "easy street". They haven't.
Writing and publishing is a long journey. There will be ups and downs, highs and lows, and having supportive people by your side as you travel this road helps tremendously. Just make sure you can spot who those are, and don't let yourself get bamboozled by the ones who see you as their ticket to easy street.