Topper has good suggestions.  We just finished a run of Murder's in the Heir and three of us had to look older.  Our audience was practically in our laps, too! 

I played the housekeeper and had to look in my 60s.  I used the brown eyeliner pencil lightly in most of my existing 'laugh lines' and any other forehead, neck, cheek, jowl, etc. lines.  I rubbed the liner pencil in a bit so it wouldn't stand out as 'drawn-on' lines. I used dark brown eye shadow under my eyes to create a 'tired' look, with a touch of white shadow just under my lower lids above the dark 'bags'.  This makes the 'bags' stand out.

When you draw the lines down next to your nose towards your mouth and jaw with the brown pencil, put some light brown shadow on top of that and white/cream shadow to highlight it.  I also highlighted my cheekbones and around my mouth (where I drew some 'pursed lip' lines).  I topped everything off with dusting of light powder just to blur the lines, and then sprayed my hair white.  Don't forget your eyebrows should be grey too.

The young guy playing the old man had to use a half-bald wig and brush-on latex to make his own skin wrinkle up.  It was difficult to use and hard to get off during intermission (same actor plays the grandson in Act 2).  We won't use that latex stuff again unless absolutely necessary.

I think that this website:  www.redbirdstudio.com has a page on makeup tips.  Good luck.