'lo, again, MangaGAF. Where should one start with CLAMP? Is starting CLAMP even worth it?
Ah, I love CLAMP.
Cardcaptor Sakura is their most popular, most least confusing and most kept in one universe series, lol. It's pretty much your general shoujo series.
Other pretty good series of theirs that isn't that confusing:
Magic Knight Rayearth
Wish
Angelic Layer
Chobits
Kobato.
The following are closely related to each other (same characters, universe), but are still pretty good stand-alone:
Man of Many Faces - More romance-y
Clamp School Detectives - General solving cases and such
Duklyon: Clamp School Defenders - Super Sentai silliness
Tokyo Babylon and its unfinished sequel
X/1999 are a lot darker than their other series but I really like them. I just wish it would be finished already.
Legal Drug and its continuation
Drug & Drop are more supernatural-y.
And finally
xxxHolic and
Tsubasa are the most confusing of the bunch. xxxHolic not so much but there are some spill over into Tsubasa. Tsubasa on the other hand is basically like Kingdom Hearts CLAMP.
You could always start with one of their earlier and shorter works to see how you feel about CLAMP. I always found them enjoyable and they are one of my favorite groups.