This first point is the one of the importance of newness. There are countless stories flooding our world every second, and it's expected that many of these will be very similar. In order to stand out or take your ideas anywhere, it is necessary to express early on in writing that you have something new and exciting to offer your readers. With something original and exciting (with the help of some great characterization) you can transform an average plot into something interesting that will make devoted followers out of your audience. Take Once Upon A Time for example. It's a TV show with an expected title, a very typical storyline (fairy tale characters are sent to our world and forget who they are while a non-magical, everyday person has to save them by believing), and characters that we already know well. This, however, is probably one of the best storyline-following shows that I know. The writers kept it from being bland by putting completely new spins on old stories that we know, and filling them with surprises and elaborate backstories and subplots. They mix characters and fairy tales in preposterous ways but somehow manage to make it work beautifully, always leaving the viewers asking, "What's next? How are they going to make this work?" and then exceeding our expectations. Feel free to follow the hero's journey archetype, don't be afraid of your story being similar to something else (because I guarantee it will be), and always have something new to add.
That first point being said, familiarity is also very important. Going back to Once Upon A Time, as I said, there are a lot of new and surprising elements added to everything, but they still are the characters and stories that you know and grew up with. Familiarity is incredibly helpful because it helps the reader become more invested in the characters and the story, it allows them to relate easier or feel a connection with what you are writing, and the reader's mind will recall any number of things and fill in any holes that you might have left. It's been said, that much of the reason many people love reading Harry Potter is because, even though there is a whole other world that was created with new creatures and laws of nature, they could reminisce when Harry went out to buy books and robes for school, when he joined the sports team, when he was nervous to ask a girl out to the dance. This sort of thing forms a bond between the reader and the writer, and can really take your writing far. So it's best to have a balance between new and familiar.
Plot holes are common and can do serious damage to your writing if left alone. For this, I would recommend rereading everything you've written to see if there are any questions left unanswered, any dramatic moments that could have been avoided, etc. Once that is done, give it to others to review with the sole purpose of finding plot holes. Bribe them. Pay them for every plot hole they can find. Commit all the necessary atrocities it takes to keep your story solid. If you want to take the Lord of the Rings route and have multiple endings to tie up all the loose ends, that's fine too. Just know that if a plot hole is major enough, it can destroy everything you've written, the readers will start looking for more to hold against you, and they will find them.
It's a great idea to come full circle in the end and remind the readers where they started. It will give a sense of completion and satisfaction, and the readers can look back and say, "Wow. Look how far we've come."
So once again, I'll tell you to read more than you write. Read before anything. There are incredible things to learn from the good as well as the bad, and once you've been exposed to a great variety of characters, plots, and themes, everything will start to fall into place naturally. Then, just trust yourself. You'll know what to do.