the thing about creating a comic, no matter how long or short, beginners tend to make the same mistakes as others.
some of these points will be about story telling, others will be about art basics, and the rest will just be common sense i've gained as an artist and a writer.
i'm not saying i'm right about everything i say, but i definitely think that its something to consider when creating your comic, especially for beginners.

DO's

*always, always, ALWAYS do your best to draw a background. it's not necessary all the time, but you need to establish a setting for at least one panel in each page of your comic. it does not matter how skilled you are at perspective or landscapes, but it matters that your readers know where your characters are. your readers will thank you for it, and it will give your comic consistency and credibility.

*always script your dialogue before you start a chapter. its important to plan ahead and make sure you don't hit a dead end or inconsistency in your story before you draw out the pages. when writing the script, you can always go back and edit information, but if you are in the middle of a chapter and you have to go back several already uploaded pages to change something important, you're letting down your readers and yourself. whether its typed on a document, or hand written on paper, its well worth your time, and your story.

*when drawing traditionally, rulers are your friend. professional artists use them, and so can you. if you can afford the paper you draw on, you can certainly afford one ruler that will last you a very long time. slanted or distorted panels are not as appealing as you think they are, and the readers do notice. and on the topic of panels, space is very important in between panels. a large amount of space between panels can be jarring to the viewer and distract them from the story, and a lack of space and blend one panel into another. straight lines and appropriate spacing can make your pages look cleaner and heighten the level of craftsmanship a work has to the viewer.

*take your time. whether its scripting or creating pages, rushing is never a good idea. craftsmanship can go a long way for a story, and it doesn't help if you rush into the story too fast. don't try to cram as much as you can into each page. give your characters time to develop with the reader, and the story will become more personal to your audience.

DONT'S

*show, not tell. the reason you're drawing a comic in the first place is so that you don't have to rely on something to tell your readers what you could establish more effectively through illustration. don't make your characters say what they're going to do. JUST DO IT. narrating can be helpful when you need to establish a setting or predicament, but heavy narration can flatten a story very quickly. if you're not going to show what's happening, you might as well write a book. ( if the narrator speaks more often than the main character, you have a problem )

*just because others are doing it, doesn't mean you have to. this can apply to a popular setting, a catchphrase, or how the comic is executed. just because a story you read started with a teenager waking up in bed late for school, does not mean you have to start your story that way as well. just because you like japan, does not mean your story has to take place there too. by doing something no one else is incorporating into their stories makes yours stand out more than you think.

*don't underestimate your audience. explaining phenomena that can easily be looked up online by the readers can slow down a story or can make it come to a complete stop. you're telling the readers that they need to be told what you think they don't know, when its possible that they already do, or hold no interest in the matter. explaining a fictional phenomena (ex: the force is midichlorians) and nonfictional phenomena (ex: space is a giant vacuum) are as different as establishing a story and talking down your audience. if the audience wants to know why space is a vacuum, they can look it up themselves, if they feel the need to know.