Self-Publishing is something that is cheap or free to do, and there are helpful resources out there. As a bonus, it may look nice to potential employers to have a book credit on your resume. Also, it is quite fun and very self-rewarding to see the final product in your hands.
I am aware of three different ones you can use, though there are probably more. I have had experience with the first two of them directly. My book on the history of the DDR scene in Japan was published through Lulu and my AIJBot Poetry book (now on Amazon) was published through Createspace.
(published through CreateSpace)
(published through Lulu)
General Notes on Online Publishing/Process
Lulu is probably the easiest place to get a book published, but there is no quality control. They don't care what you set to print, they'll publish it, but do this at your own risk. The default option is to only publish on lulu.com, which is fine, but if you opt to have it published on Amazon as well (which did require a small fee when I used them last), they may step in and hold up your publishing progress since they reserve the right to refuse poorly printed/illegible/bad/unprintable material. However, the big advantage of this lack of proofing is that if you spot a mistake or need to overwrite your documents, make a new cover, update your book info. etc., you can do it immediately and the changes will take effect immediately.
One other disadvantage of Lulu is the distribution network. The prices have come down in recent years from what I understand but they are still more expensive than say, Amazon. If you are looking to make a profit, lulu is going to take a bit more off the top than other places.
With Createspace you have similar options, though they will not only put your book on Amazon but help with wider distribution nets (for a price: $39 US at this time). That would help you expand to more worldwide distributors (including the different Amazons of the world) as well as actual bookstores. You also get slightly more profit per sale if you opt for the extended distribution option since that puts you in their "Gold" club.
The process is well defined through Createspace; very similar to Lulu in fact, though there are some key differences that may hold up your progress (though probably for your own good in some cases). The first thing to note is that everything you submit is subject to review by their system. They have taken issue with images (do you own the right to use them?), they will not allow you to say in the book that "Amazon" is the publisher (for whatever reason I forget now), and other small copyright points. This means that after you submit files for review, there is a waiting period of up to a day or two before you can continue. This peaks when you submit the book interior and are ready for the proof copy. You *must* order a proof copy before Createspace will let you publish the final thing. Once you order it, you can then choose to publish it at that point before you receive it, but it is strongly recommended you take a look in print form first since some things jump out at you on paper where they didn't on screen. Also, once your book is "published", you will jump through many hoops if you want anything changed, because it affects not only your createspace page, but anything on Amazon.
I honestly don't know too much about Lightning Source except that they are a printing center first and foremost and they just happen to publish as well. Also, they demand very specific types of PDFs for submission (I can't remember the specific format but it was one you had to tweak settings in some Adobe app to get). It had to conform to that standard or you couldn't submit anything.
Important Points - Interior
Regardless of what you use to write your book, in the end you will be exporting to PDF.
Also, remember that the first page of your book is actually the right side page facing you, the second being the back of that page, and so forth (go open a book and take a look if you don't know what I mean). This means your book must have an even number of pages. Add a blank one somewhere if you need it. Viewing your book and setting your pagination in something like Word can be confusing because Word lays out your book like this:
However, when your book is printed, the pages look like this:
To check how it will really look, open your PDF in Acrobat, go to the View Menu, choose Page Display > Show Cover Page during Two-up and also select Page Display > Two-up Continuous.
Include all pages in a single PDF file, with the front cover at the beginning, and the back cover at the end. Ignore the book spine (that is done when creating the cover).
If at all possible, make the PDF text-based, not image-based. In other words, avoid creating your file from full-page scans or rasterized page images. (But the covers can be images.)
A page in the file must show only one page in the book, and the dimensions should equal the book’s trim size. In other words, don’t output the PDF as two-page spreads instead of individual pages. Don’t submit PDFs at 8.5 x 11 inches with a small centered text block. Don’t include bleed or slug areas.
Embed and subset all fonts. You can do this at the export to PDF phase. In PrimoPDF (what I used), I set the option to "Prepress"
Non-vector images should be exactly 200 pixels per inch. The same goes for page scans, if you use them.
Images should be in RGB, grayscale, or monochrome. Do not use CMYK. Use an sRGB profile for RGB images, and Gamma 2.2 for grayscale ones, with profiles embedded. (If you don’t know what any of this means or don’t know how to do it, then never mind.)
When generating the PDF (not before) apply JPEG compression to color and grayscale images, but at the highest quality that allows the file size to be reasonable for uploading. Monochrome images should also be compressed. The maximum file size should be no greater than 500MB.
Also, if at all possible, do all your graphic editing in a separate program and plug them into your book as-is. If you rotate something in Word/InDesign such as WordArt or some random clipart image, the exported PDF will sometimes have a grey border around it that does not *usually* come out when printing; only visible on screen, but there are random cases where the border is visible, and this only happens for rotated graphics as far as I have seen.
Oh yes, do not add any type of security like a password.
Important Points - Cover
With Lulu and Createspace, they have their own Cover Creator app you can use. The designs are pretty basic but there is quite a bit of variety. Just upload your own pictures, edit the titles and description and you are good to go. You can go on your own for this part and use a template file but really, it is *much* easier to use the Cover Creator unless you have something *very* specific you can't reproduce otherwise.
Important Points - Advertising/Publicity
With Lulu and Createspace, you are given your own page which you can customize, including customizable previews. On Amazon, however, you are at their mercy. They take whatever info. CreateSpace or Lulu fires at them and uses it as it. This may not be a problem, but if you want to change something, be prepared for a lot of red tape and obscure contact paths and waiting to get anything done. Also, Amazon has that "Look Inside" feature, which is nice, but once you click "Agree" to their conditions, they will pick some arbitrary section of the book to show, and you can't easily edit or even delete it. Be warned.
I also made a Facebook page for my AIJBot Poetry book but you could also use Google+ for that, too. You could also set up twitter or even a blogger account for it if you really wanted.
Important Points - Electronic Publishing
It is possible to publish through Amazon for the Kindle. I do not know much about this phase but I am looking into it. It is easy enough to convert a document with Calibre (if you have an eBook reader, get this *now* if you don't have it), but putting it on sale and formatting it so they will be happy is another story. You can also DRM your work, but I'm against DRM in general, so I'm not the best person to ask about that.