Quickly add text to existing pdf files / fill forms

I have a really amazing bit of technical wizardry that helps me to do this. It's called a Rectangular Uniform Long-Edge Reader. You need a your document in Pointed Regular Inked Neat Typeset Editable Document form. Once you have that, place the Rectangular Uniform Long-Edge Reader against the Pointed Regular Inked Neat Typeset Editable Document and the Reader will magically tell you where the boxes are!

That said, I usually just use something like xournal or jarnal to do this as it saves Perishable Absorbent Pulped Environmental Resources.

I do what you do with pdfpages and absolute positioning, but...

...this is one occasion where it helps immensely to have a live updating PDF previewer which will automatically live-update as you edit, so you don't need to hit recompile whenever you make a small tweak to a positioning parameter.

There are a few of those available, at least for GNU/Linux systems:

gummi LaTeX editor

whizzytex (for emacs)

live-latex-preview script for vim + mupdf

I'm not sure what works/what's available like this for other OSes.