Artists come in all shapes and sizes and from different places on the internet. Some are on pixiv, some only have their own websites, and some have art that randomly appears and then you never hear from them again. Here's a simple guide to getting the names of the ones you want and putting them up on shuu.
Starting off at Pixiv
When you're on pixiv and happen to find an image you like, you may decide to post it. If this occurs you shouldn't simply put up the image and forget about the artist. You're on the most artist-based image board there is! Instead, do the tagging team a favor and look for the artist's name yourself.
Some artists only have a pixiv account. In this case, their real name is their pixiv name. So, take the name or Japanese characters under their avatar (or on the profile at the bottom of the artist's main page) and put it in misc. metadata. Someone will add it for you or translate it for you with little to no effort.
Artists that have a website on their profile are different. You need to go to that artist's website and see if you can find their name there. Usually, these artists' names are not the same as their pixiv nicks. Artists' blogs and websites are the main source for a name. If you simply cannot find a name on the site/blog, ask someone else to take a look before giving up and taking the pixiv name. Sometimes those with experience (or Japanese skills) can find things more readily than you.
Most artists don't have the convenient little "author" written right on the front page of their website. Look for an "about", "profile", "info", or "link" page. On these pages you have the highest chance of finding an artist's name. If the site page names are in Japanese, look for "プロファイル", "インフォ", "アバウト", or "管理人". In any case, if you simply open all of the links you'll stumble onto it eventually. On these pages, the information usually comes after either "PN", "HN", "管理人", "名前", etc. Things like "サイト名" or "HP" are generally the name of the website. These are never the artist's name.
Shuushuu to Pixiv
You should first see Signing Up On Pixiv. You start off on shuu with a picture you like. "Oh, that's so nice," you think to yourself. Good, click the "show all information button". Is the file name a string of seven or so numbers? Copy it:
Then go to pixiv, and click one of the images found anywhere on the page. See the url?
Replace those numbers at the end with the ones you just copied and hit enter. The image you liked has now magically appeared! Click on the artist's face or the プロフィールを見る text to go to their main page. The nick on pixiv for this image is nicolla, but they have a website. Next click on the website (this is imperative for finding the correct name of the artist). Oh look, there is a discrepancy:
"Vanilla" is the name according to the blog. So what do you take? Vanilla.
Shuushuu to Piapro
If the original filename looks like one of these:
then it is most likely from Piapro. Piapro is a site dedicated to Vocaloid media (illustrations, music, song lyrics, etc.) Their filenames are in this format: "PictureTitle_ArtistLogin_SomeNumbers.jpg"
It's easy to find the artist from this filename.
Then paste it in your address bar after "piapro.jp/". In this example you would get http://piapro.jp/akaiya3. Tada! You are at the artist page. To see the artist's full profile, paste their login after "http://piapro.jp/my_page/?view=profile&pid=". For example: http://piapro.jp/my_page/?view=profile&pid=akaiya3
Be aware that Piapro automatically appends "さん" to all of its user's names. Don't use this as part of the artist name when making tags or wiki entries.
Boorus to Pixiv
Some of the art of shuu comes from a booru, be it danbooru, gelbooru, moe.imouto, etc. Of all the boorus, only moe.imouto and danbooru have any sort of a reliable system for finding artist websites. While many of the names at these places are wrong, the links don't lie. A typical moe.imouto sidebar for an image from pixiv looks like this:
The source section will link you right to the image on pixiv, and if you click the question mark next to the artist's name (yellow on moe.imouto, red on danbooru), you may or may not be linked to a page with the artist's websites on it. This works in the same manner on danbooru. You can then look at these websites to double check the information yourself before doing anything with it.