What general tips do you have for golfing in Emotinomicon? I'm looking for ideas that can be applied to code golf problems in general that are at least somewhat specific to Emotinomicon (e.g. "remove comments" is not an answer).
Please post one tip per answer.
Should be answers to respective challenges (if they exist). Note that some of these code samples might alerady be answers somewhere else.
If you just want to print undefined, use this 4-byte, 1-char program.
π¨ Infinite loop (6 bytes, 2 chars).
βΉβ© Cat (owned by Conor O'Brien) (15 bytes, 5 chars).
β«βͺβ¬β«β© This program should output the 8 phases of the moon, but it doesn't seem to work (61 bytes, 16 chars).
ππππππππππ²βͺβ¬π·β©ππ¬ Hypothenuse (27 bytes, 7 chars).
πΌπ£πΌπ£βππ¨ 
If you just want a truthy value (or even just a value), without using it, use βΉ. It's 3 bytes, while the others are 4 bytes.
If you want to output 2 chars or less, do not use βͺβ¬β©, use the number of β¬s needed.
If you want to loop a program infinitely, from index n, you can use n㪠to jump behind the nth character. For example, this 34-byte, 12-char program for yes:
πβͺπseyπ²βͺβ¬β©πβ© Becomes this 32-byte, 11-char program:
ππseyπ²βͺβ¬β©ππ¬ 
yes idea originated here. \$\endgroup\$ Some cases are:
βοΈβ -> β0-10, 100 and i are ππ
ππππππ‘ππππ―βΉ, respectively.2-4 is done with πβΊοΈπ, respectively.2-4 is done with πππ, respectively.2-4 is done with π£ππ, respectively.n being 2-4 is done with πππ, respectively.n, use π
nβπ. n is not a literal n, but the power of rooting.Because of a bug in the interpreter, if you want to append 1 to a number (e.g. 10 -> 101), use π. As it is right now, you have to use π
β for the true function of π.
"123"+1 -> "1231". \$\endgroup\$