As you remember, there are four accentual (stressing) paradigms of nouns, adjectives and other declinable parts of speech. Each Lithuanian word is stressed by one of these paradigms (only one for a word). When you learn new words, you must also memorize their stressing paradigm. In most dictionaries, the number of a paradigm should be indicated in parentheses next to a word, for example: lempa (1), pieštukas (2), kambarys (3), stalas (4).

The 1st paradigm makes a word always be stressed in the stem:

lempa (a lamp)
lempos
lempai
lempą
lempa
lempoje
lempa!

lempos (lamps)
lempų
lempoms
lempas
lempomis
lempose
lempos!

Here are some more examples of nouns and adjectives of various declensions that fall to the first paradigm: