When it's time to start sketching your comic out, you have to decide whether you plan to draw the page or individual frames. Basically, many artists actually draw individual frames by themselves.

Frames sketched out without planning the final arrangement beforehand and the final comic's look ...

They usually have a vague idea of what they want on the page, but they'll wait to do the arrangement until later. Most often, if that is the case, they don't put all the frames together until they have all the other steps done; after it's colored and finished up.

I personally believe it's a lot better to try and design things before you start drawing. The arrangement of your piece being sloppy is one of the biggest things that can detract from your artwork looking professional.

The comic sketched out, taking into account for the final arrangement...

If you plan everything out before you start, you can make sure your layout will work in advance and you can redo things before you are too far along.

Having a lot of good "flow"
The thing you want to focus on is making sure everything flows smoothly. You want your reader to read through the frames in the order you intended, and it's also important that they don't read the speech out of order. To top it all off, you need to think about how your work looks within the space. Just because you're not doing a simple image or painting, doesn't mean you don't want to have a good composition. If you don't know what I'm talking about, visit this link. We're talking about the golden mean and more commonly, the rule of thirds. Basically you want to stay away from putting the focus of your picture in the center of your composition. You can do bulls-eye effects occasionally, but only in the midst of normally avoiding them. You should always off-center a least a little, such as the middle scene in the comic below.

The rule of thirds applied to the comic's frames.

Not only do you want your art to look good within each frame, but you should try as hard as possible to follow the rule of thirds for your overall page as well! Creating a comic layout can be even harder than when painting a picture, but it's the one of the most utterly important things about creating a successful comic.

The rule of thirds applies to the page as a whole as well.

Here's a great guide to arranging elements of your page.

Over time, I've learned this is actually one of the hardest concepts for people to master. The problem is that people have learned to press hard when they write. The reason it creates problems when you draw is that if you have to correct yourself, there's a faint line still left behind.

Even after tons of erasing, an image drawn with too much pressure won't come up.

That also happens when you erase the line work after you finish inking.

Basically, everyone needs to learn to draw lightly. It's very hard for some, and it's something they have to work on.One of the easiest ways to teach yourself, is to hold your pencil towards the eraser end.

The only way to get good at something is to practice!

It will be very loose and hard to do details, but the point is not to actually create comics this way. You're trying to teach yourself to draw lightly. This is practice. The hope will be that if you do this over and over a few times while trying to sketch, when you go to actually create work for real, even though you'll be holding the pencil as you used too, you can press lightly on the paper.

This is the part that you would be actually working on the arrangement, and you would most likely sketch out your basics shapes of people and get their positions and angles situated. You should be focusing on simple shapes or lines to represent your people. A lot of people think of it as the "stick figure" portion, although it can actually be a bit more complicated than "stick figures".

Two different styles for crafting out your comic layout...

Some people actually skip this step, although for most it helps. I personally try to work everything out in my head, simply visualizing the page and re-arranging it before I draw. That doesn't always work for everyone though. You should focus on what works the best for you, as your goal is producing the best quality page possible.

After you establish your basic shapes, you can begin drawing out your characters and scenes. You have the option of drawing directly on the sketch or of starting with a fresh piece of paper. Most of the time if your sketch is drawn light enough to erase later, it won't matter.

The final sketch, ready to begin inking.

You have to focus on details and getting your image to represent the final product as close as you can with simple pencil line-work.

There are a lot of artists out there that produce comics in plain pencil. Honestly, most are webcomics as very few comic books are printed that aren't done at least ink like manga is.There aren't a lot of big success stories out there. The main one that comes to mind is Megatokyo.

If you're aiming to publish your comic simply as a webcomic, you can feel free to produce comics however you want. If you want to finish and refine your pencil comic, it's perfectly acceptable, although many webcomic readers are deterred from reading these type of comics at first, as there are so many webcomics out there. Manga format, with inked artwork and texturing is a little more popular, often with full color topping the list.

None-the-less, if you have the choice of your pencil work being the finished product or whether you just want to use it as the base to draw the rest of your art on. If you plan to create a finished professional looking pencil comic, you need to focus on cleaning up details, and on using dynamic lines to help certain areas to stand out.

A picture finished entirely in pencil...

You're going to be going over your original lighter lines with darker lines to finish things out. Other than that, it's about all the same rules apply. You want to start out with light lines so you can erase, only ending with dark permanent artwork at the end. If you do decide to go for more, then you're ready to go on to the next step.