The Strong Word and the Weak Word
One of the bigger things you will have to wrap your head around is that Gothic differentiates between a "strong" word, a "weak" word, and has an "other" category. What does this all mean? A word which is in strong form is a word that will have a vowel changed to move it into another tense. A word which is in weak form will have its ending changed in order to demonstrate its tense, or timing. Other forms will experience a different change when using words. In Gothic, the verb(or action word) would be in strong form or weak form depending on which noun(a person, place or thing) is used.
Note that the Germanic Strength of a word is different from another term of grammar which is related to how a word will be pronnounced in a sentence.