I was working on crans tonight when it occured to me that I have absolutely no idea where to isert them in actual tunes and I’ve only seen them actually marked in occasionally. I know that roles are often used to break up otherwise boring dotted quarter notes and taps and cuts are used to separate like notes/where ever, but I have don’t really know the pattern for where crans are appropriate. Can anyone enlighten me or should I stop worrying?
there is another topic by is i myself I did, search, all the details on using crans like where and when. luck!!
when you need 3 D,s or 3E.s---------------
What Cavefish said. A good tune to practice cranns on can be Morrison’s jig. Rather than playing a roll on the E in the first measure (and those following where you’d do a roll), a crann can sound pretty neat, followed by either a roll on the A or just ABA (rolls on an A can be difficult).
Try the D crann in Fraher’s Jig:
http://www.thesession.org/tunes/display/992
http://www.youtube.com/watch?v=1aLLE6Wh7QM
BTW, I would not dismiss playing the quarter or dotted quarter as-is as boring. 
I’ll second the Fraher’s Jig suggestion. This tune helped me learn to play cranns and understand something about using them.
paddy fahy and swallowtail jig--------------what is your email i will send you some short clips as i play these tunes 
just to get an idea------------------crans are a must
The beginning of Blarney Pilgrem takes a cran.
Also the second part of Foxhunter’s Reel.
Also the fourth part of O’Farrell’s takes one.
Also the third part of Frieze Breeches.
… and the beginning of Sean Bui (Yellow John)
The Salamanca
The Newly Mown Meadow
The Chorus Reel.
Repeal of the Union
Within A Mile of Dublin
The Home Ruler
I think of a cran as a substitue for a roll on the D note. On a whistle it is not possible to “roll” on a low d because there is no note below the D and a roll is a triplet figure with a cut and a strike you can’t strike on a low D because there is no other hole to strike on. So if you know where to place a roll it shouldn’t be difficult to place a cran on a D or E that could use a roll. The tunes above use lots of crans as they are in D and the root note is used a lot. I would add to that list:
Lucy Cambell’s
The Foxhunter’s Reel
The Humours of Glendart
this too------------its all up to YOU
Does anyone ever “cran” on higher notes, F and G in particular? Cuts came easier for me than taps (still do) and I sometimes find myself playing G T1 G T2 G or F T2 F T3 F, instead of G T2 G B1 G.
I sometimes use a sort of quick two-cut crann on G and A using the C and B fingers.
The Dusty Miller (slip jig) I think is a great tune for practicing cranns.
The Frieze Britches is another good one. Cran on all of the DEDs.