Second - Leprechauns are pretty CLEVER, so you have to be tricky. We like to hang signs that say things like, "Leprechauns Welcome" or "This is not a trap!" You can download them here if you would like to use them. We have even tried to make ours look like a little Leprechaun home.
Third - Just like any magical creature, leprechauns love sweets. So leave a treat of some kind. We like to leave a little crumb of bread with honey. Really anything sweet works, but you know how much the little green men like gold things, so honey seems to be a good choice.
Fourth - you must make your trap. There is something about a trap from the store that tips them off. They seem to smell those traps from miles away. They won't even get close. And every trap has to be different or else they get suspicious! Anything you make works though! Try Legos, shoe boxes, oatmeal cartons, nets... anything! How will you trap yours?
Fifth - BAIT! You have to leave bait. What do you use for bait? Why GOLD, of course! Again, anything seems to work. The shinier the better! We have tried pennies, gold ribbon, sprinkles, honey, confetti... be careful though! Don't use anything very valuable because, if that rascally leprechaun escapes, and chances are he will, he just might take your beautiful golden bait with him! Now, we have been lucky and our leprechaun has always left chocolate gold as a treat for us (even though they are tricky, a leprechaun is honest and fair and won't take your gold without leaving something to trade with.) We have found gold wrapped coins, rolos, and even peanut butter cups. I have been told they sometimes leave a trail of green glitter or gold dust. They've been known to turn our milk and even our toilet water green. And one year, he even left a tiny green footprint behind with a note that said, "Ha! Ha! Fooled you again!"