Long toss before pitching sounds good. At a Red Sox game not long ago, that is exactly what Josh Beckett did for his pre-game. Prior to going into the bullpen to pitch his warm up, he did long toss in the outfield, started fairly short distance then went long, then longer, moved it back in for a few then went to the bullpen and started pitching at maybe 75% and worked up to game speed from there.
My son and I do something like that when he throws a bullpen, although we usually do a long toss and pitch bullpen on one day and don't do any fielding that day, if anything he might hit some afterwards. Then on a fielding day we'll do long toss to warm up, do the fielding, and if we have time do some Batting practice. Usually don't field and throw after pitching a bullpen. I'm not sure that there's anything wrond with that, we just haven't done that much. Maybe because it mentally separates the two types of throwing mechanics, pitching and infield. More of a mental thing, although after a good bullpen it isn't a bad thing to lay off the throwing. Depends on the amount and intensity of the bullpen.