Many aspects of Xcode’s editing environment can be modified to suit your tastes. Your first step should be to pick a font face and size you like in the Fonts & Colors preference pane. Nothing is so important as being able to read and write code comfortably! I like a largish size (14 or even 16) and a pleasant monospaced font such as Monaco, Menlo, or Consolas (or the freeware Inconsolata).
Xcode has some formatting, autotyping, and text selection features adapted for Objective-C. Exactly how these behave depends upon your settings in the Editing and Indentation tabs of Xcode’s Text Editing preference pane. I’m not going to describe these settings in detail, but I urge you to take advantage of them. Under Editing, I like to check just about everything, including Line Numbers; visible line numbers are useful when debugging. Under Indentation, I like to have just about everything checked too; I find the way Xcode lays out Objective-C code to be excellent with these settings.
If you like Xcode’s smart syntax-aware indenting, but you find that once in a while a line of code isn’t indenting itself correctly, try choosing Editor → Structure → Re-indent (Control-I), which autoindents the current line. (Autoindent problems can also be caused by incorrect syntax earlier in the file, so hunt for that too.)
Under Editing, notice “Balance brackets in Objective-C method calls.” If this option is checked, then when you type a closing square bracket after some text, Xcode intelligently ...