Guys/Gals: First time I have taken over maintenance for an apartment complex, not the biggest but.... I've replaced bad spray heads, it's got lots of those, fixed a pipe with a landscape spike stuck through it for several years, and now it's the end of the month. Do you bill for time & material? Do you charge a set amount per head? Some heads are simply screw out old, screw in new, some more complicated. Any of your help would be appreciated, trying to be fair. And I don't want to start doing it one way, and then try to change it to a different way.