Not really what I was expecting -when I decided to actually create a weekend warrior rock group, rather then just jam with dudes or happen into groups- was the task of singing while playing - the job of "Frontman".  I used to think that was a stupid title.  But in a 3-piece, where you are the defacto singer and, in my case, the only guitarist, it seems a very appropriate title, and no small job. 
My last group was a classic rock righ with 9 members (3 guitars already), so I was recruited as a "fill-in" drummer.  That band found a new drummer and "let go" of a guitarist to move me there.  We had fun, but I was constantly trying to find quiet space between the other guitarists' notes to add to the songs. Many of the members showed up ill-prepared, which meant full band rehearsals were used for individuals learning there parts.  Just organizing rehearsals with 9 guys that had day jobs was regularly an excercize in infuriation.  I became frustrated.
The good news is that the drummer and bassist both sort of felt the same way and wanted to step up their game too.  "Ok, lets get together!!"  We did, and quickly found that we could all jam the 30 minute 12-bar blues, or scratch out some of the big band tunes we were playing, neither of which appealed to us.  After asking and finding out that we had a very short list of SONGS that we all three knew, we decided to create a list over beers, learn them, and return a week later.
Now that we know tha songs, "who's going to sing them?".  The drummer has never sung and has no plans of it.  Rightly so.  Bassist knows a few songs, but really sits in the pocket well as a dedicated bassist.  Ive tried singing while playing and have only squeezed out a few songs that way.  Finding a good singer willing to jump into a startup that plays out once a week has proven unfruitful, so far.  Most of the musician classifieds are searching for singers and most have established gigs to offer.
So, the trudgery begins.  Playing and singing.  I think maybe it should be renamed to "Playsinging" or something to identify that the two jobs are completed simultaneously.  Each of these takes years to master, so does that mean that I have years to work on Playsinging to master that job?  We call it a "Frontman", I think because you, as the singer, guitarist(or other) and guy-in-front(or behind if your on the drums) now must also communicate with the crowd between songs,  know all the guitar parts, run the set list, and oh, yeah SING!
But, I'm a guitarist, not a singer.  Sure, I try to sing in the car or shower, along with songs, but pulling off lead vocals without hurting people is not short of difficult.  So, I have gathered my thoughts, and would very much appreciate more in return, on how to get the Frontman job done.

• Know and practice the songs inside and out only on your guitar (or other instrument). Be able to play them almost automatically.  Depending on your abilities, cutting out some guitar trickery might buy you some brain power.
• Know and practice the songs inside and out with your voice.  You should be able to sing the entire song with nothing more than a metronome.  Other music queues naturally help, but a lot of musicians, like my drummer, do a lot of keying off the lyrics.
• Practice Playsinging (wow, really?).  This must almost be automatic too, if you wish to look better than just standing there with guitar face, muti-tasking through the songs.
• Practice the live show in your basement or garage.  Set up your gear and set list completely, patches, backups, whatever.  Decide at least when you will address the crowd, for rapport, a stall for a guitar or tuning change, introductions, etc.  Time the whole thing.
• Simplify.  If you have stomps or a full rack, try to set up groups of songs on your gear.  This may take a script, if you have a huge setup.  Personally, having a solid state modelling amp with an integrated foot switch can make your life a whole lot simpler.  When you were a dedicated gunslinger you had more time to futz with it.

So, hopefully you have more to add here, maybe you have one of those tricks that lets me bypass hundreds of hours practicing - probably not.
Chris