Styles:
https://www.dreamwidth.org/customize/
* the Mobility base style, which is specifically designed to be usable on mobile; sadly it has only two themes at the moment; there may be other styles that are mobile-friendly, but this one is specific.
* Single column page setup

Settings:
Display tab:
https://www.dreamwidth.org/manage/settings/?cat=display
Journal Pages: Shown to You: You can override other people's styles with a few options.
Navigation Strip: has a convenient shortcut to view other journals in different ways
Comment pages: if you have trouble with reading comments in other styles, pick your preference here
Comment Hierarchy: if you're having trouble with threading, especially deep threads, this shows a textual description, for example 2a3d would be the second thread, the first reply to the thread, the third reply to that parent, and the fourth reply to the previous parent. If you can read multiple levels of numbered headings in a list or paper, you'll have practice at this.
Mobile View: Dreamwidth tries to make things mobile friendly on modern pages, but if your device is large enough that it really can display the page like desktop and it's serving you just infuriatingly tiny slices, override that here.
Site Skin: a few options here; there are two with non-expanding menus which helps with no mouse, and Lynx is a really pared down skin that lets your mobile browser do most of the display work.

Mobile tab:
https://www.dreamwidth.org/manage/settings/?cat=mobile
This is just for post-by-email, which you may prefer as a mobile client to the site update page, especially if your email handles drafts better. (There have been some drafts improvements, but the main one hasn't been around long enough for me to know how much I trust it yet.)

Shortcuts:
https://www.dreamwidth.org/manage/settings/?cat=shortcuts
Do you like using gestures or keyboard commands? Set those here.

Privacy:
https://www.dreamwidth.org/manage/settings/?cat=privacy
Minimum entry security: if you would like to post most entries locked but aren't sure how to do that by email, you can set the minimum entry security to set everything to friends-only. (You can edit entries after they've posted to public if you want.)

Beta testing:
https://www.dreamwidth.org/beta
If you'd like to try the new entry page or new inbox design, opt in to those here. I love the new entry page; it performs delightfully for me on mobile. However, it does not have a rich text editor yet, because the RTE is still a bear that needs wrestling in order to get it updated. I am reliably informed that the old janky RTE is in the new entry page as of last code push!

On the new Create Entries page:
https://www.dreamwidth.org/entry/new
Select the Settings gear in order to adjust the number of columns on the page (1 or 2), show and hide panels, and drag panels around until you like the layout.