First thing is to define what full livery means, as it needs to be both what you expect and the client to, but there's no accepted definition.
For example, some people would regard full livery as being everything, stable, turnout and in, grooming, all forage and hard feed and riding exercise, poo picking, worming, farrier visit attendance and all tack cleaning. Basically in other words they just turn up if they fancy riding, and not if they don't.
Some other people would see it as all of the above but without the tack cleaning, others wouldn't expect the horse to be exercised but maybe put on a walker 3 times a week, others still may not expect any exercising.
Also, full livery would generally be expected to cover weekends and bank holidays including Xmas and new year etc, so cover would need to be made for that.
It doesn't really matter what definition out of the above is adopted, as long as its really clear to the client what is included in 'full'
Also full livery clients will be less tolerant of standards not being kept up so it's important as the previous poster said, to charge enough to allow sufficient maintenance and renewal of facilities and staff cover over time.
I think in some ways full liveries can be less trouble than DIYs as you can make sure the horse isn't neglected and is well looked after and the jobs are done.