(Updated answer including information from the comments)
Remove unwanted ligatures. (Standard LaTeX ligatures are ff, fl, fi, ffl and ffi.). babel
offers the shorthand "|
, which you can insert in between the ligaturized letters, for most languages but not english
(neither italian
and norsk
). If you're writing in on of these languages, you can either use {}
instead, or easily activate the shorthands as described in babel: Adding ngerman' s language shorthands to english as the main document language. For the ligatures, it shouldn't make any difference.
I haven't yet found a comprehensive guide to when ligatures are desired or not, but I do know that you don't want a ligature across the border of two morphemes, i.e. two "morphological units" or somewhat less correct but perhaps more graspable two "semantic units". (Morpheme borders may or often may not coincide with syllable borders; syllables are not the same as morphemes!) I asked a question on this topic at english.sx: When should I not use a ligature in English typesetting?
An example from German: Auflage would usually be compiled with an "fl" ligature. However, it is a compound word that consists of two morphemes: {auf} + {lage}. Thus, the ligature should be suppressed by coding it as Auf"|lage
. Similarly with auf"|fallen
.
Comparable English examples might be off"|line
or stiff"|ly
, but I'm not 100% sure on these.
Searching the source code via Ctrl+F & friends makes finding ligatures pretty convenient, and with a little practice, you can determine whether a ligature is necessary or not within a second. For a 200-page book, it might still take you a while. There's a script for German texts that does this job for you: http://ctan.org/tex-archive/support/rmligs or a more recent version at the creator's homepage http://www.j3e.de/ispell/igerman98/dict/.
So if you notice you're de-ligaturizing the same words over and over again, the question Can one (more or less) automatically suppress ligatures for certain words? might be interesting to you. Mico is taking up the challenge of writing a package that avoids undesired ligatures automatically: Any suggestions/requests for features for a new package that allows disabling ligatures for (pre)selected words?