-cona   -less, without 'X'
elestė ("star") – elestecona ("starless")
alnė ("time") – alnecona ("timeless")

-clui / -cla   -ward, toward a certain direction
Use -clui when the word is an adverb (like in the sentence, "He went northward."):
      lamedė ("west") – lamedeclui ("westward")
Use -cla when the word is an adjective (like in the sentence, "Carry on, my wayward son." [also the title of a song] ):
      nuivė ("way") – nuivecla ("wayward")

-elqua   -ful
mati ("to forget") – matelqua - ("forgetful")

lil-   -ling, semi-, an immature and/or small form of something
bubulė ("dog") – lilbubulė ("puppy")
miaulė ("cat") – lilmiaulė ("kitten")
asindrė ("tree") – lilasindrė ("sapling")

-lba   -able
parthi ("to pay") – parthalba ("payable" or "affordable")
galethri ("to survive") – galethralba ("survivable")

ne(n)-  un-, the opposite of the root (like mal- in Esperanto) on common adjectives
Ne- is used if the following letter is a consonant:
      ninya ("new") – neninya ("old")
Nen- is used if the following letter is a vowel:
      įtala ("high" or "tall") – nenįtala ("short")

pet-  to make something happen
aneldi ("to learn") – petaneldi ("to make learn" or "to teach")
unquami ("to die") – petunquami ("to kill")