caveat: the
front ends available for LP leave a lot to be desired
and unless you like writing scores in a markup language (see below) then
I suggest something like Musescore
Yet if your final aim is to do notation typesetting/publishing the
challenge is worth it.
Let me mention that if you are also a composer, you may be interested
that Rosegarden has very good (although not perfect) export to Lilypond,
while giving you a very powerful composition environment.