Having added fields to a layout, there are several "shortcuts" that can help position them neatly:
Click and drag fields to organize them neatly beside or underneath each other. Don't worry if they don't line up precisely. When you're relatively satisfied with the layout, select all the fields you would like to arrange neatly: Use the Ctrl-key (Command on Mac) to select one field after another, making sure to click last the field which has the left adjustment you would like to preserve. Then right-click to bring up the context menu and choose Align left.
The same can be done to distribute evenly fields that are placed one below the next, and to make the fields the same width. Remember that it's always the last selected field's left/right adjustment / width that determines the adjustment of the other fields in the selection.
To resize a single field, simply select it and use the little squares in its corners to adjust the field's size.
By selecting several fields and right-clicking to open the context menu, it is possible to make all the selected fields the same width/height and so on. Try it!
A note about bag fields
Certain fields are bag fields, i.e. they can contain more than one entry. A typical bag field is the Keywords field (#025)in the standard field definition, which typically contains a collection of individual keywords. Although these bag fields can be shrunk to appear as a single line field, for optimum control you should expand them to show the full bag field layout with optional quicklist controls for quick metadata input.