It can be as simple as having people believe in you as a writer (regardless of how low your royalty checks are at first and the lack of publishing advances in your attempt to go it alone), believe in you as a person to give you the time to your insane hobby, or as complicated as an actual publishing deal with editors and agents involved. It can be a beta reader or an advanced reader. A reviewer or a fan.
But whatever it is, whatever they are, a good support team is necessary to be able to write at all, let alone successfully.
Moral SupportersYour family, be it extended or immediate, blood or adopted, is the first tier of your support team. Unless you have professional writers or readers in your family though, the support they offer is nearly always going to be of the moral support realm as opposed to the technical support. This is not to be underestimated.
It is important to have a supportive family in everything you do (or at least the absence of a family that is countersupportive). If writing is something that you have to hide from your loved ones, then you will either develop a split personality or one will win out. Writing is not for the faint of heart and definitely not for those that cannot throw their soul into the all-consuming fire that is professional writing (be it successful professional or unsuccessful). For people that want to cross the border between writing as a hobby and being a writer, there are no half-measures. This cannot be something that you do as a hobby and it cannot be something that you do when you "feel like it".
Writing is your life, and it is important that your family is also part of that.
It's up to the individual to access their relationship with their family to see if they want to allow advanced copies. There are a plethora of reasons why you might not want to, and most are acceptable excuses to not allow it.
Still, family is not to be relied on as readers in general. Unless they have the same interests or likes as your book offers them, why expect them to read a book merely because it is from you?
On the other hand, you can probably count on them to be your first few sales. I recommend not hounding them for results. In my experience, even asking them more than once will foster negativity.
Technical SupportersThose in your circles that do have professional experience, be they writers of their own works, editors, agents, or even just voracious readers that are aware of the written word as well as the story will form your primary tier of technical support. These are your companions into the dark abyss of writing that will provide the first non-you viewpoints of your work (although probably not objective). They are your beta readers and those that believe in your work as a story or in you as a writer.
They can be harsh and critical (and if you pay them, it is hoped they are more objective than not), but they are frequently sensitive of you as well. It is your job to put them at ease and draw out their true opinions. And ultimately, it is your job to be able to reject their opinions or understand their viewpoint.
Although the remedy they may recommend to you is not always the solution you are looking for, it is at least proof of the existence of a malady.
Then it is up to you to be the doctor of your own work.
Final SupportAt the end of the day, your support team is there to support you. Whether you are out there without a safety net or you have the strength of a thousand behind you and believing in you and your work, you are the one being buoyed or flying alone. It is up to you to reward their faith or earn it.
At the end of the night, when you are alone with the glow of your monitor and the hum of your hard drive, you still have your words.
If your words can inspire your faith and belief, then you can continue on in your endeavors no matter the pain and doubt.
Pour yourself into your writing and continue to improve. Be the best that you can be no matter what may befall you.
Remember in the world of today: once written and published, your words will exist forever.
Write the words that will inspire not just friends, family, colleagues and associates, but write the words that inspire you. Write the words that inspire everyone.