Verb groups: not every る is the same
Accurate conjugation requires both a verb's dictionary form and its group. Verbs ending in る do not all change in the same way.
Start with three groups
Beginner materials commonly use groups 1, 2, and 3, corresponding to godan, ichidan, and irregular verbs. Names vary between textbooks, but 書く (write), 食べる (eat), and する (do) provide useful comparison points.
In group 1, the ending changes, as in 書く → 書きます / 書かない. In group 2, remove the final る and attach the required ending, as in 食べる → 食べます / 食べない.
Check verbs ending in る
見る, 起きる, and 食べる are group 2, but 帰る, 入る, and 走る are group 1. In particular, an iru or eru ending does not guarantee group 2; check the dictionary's conjugation information.
着る (wear) is read きる and becomes 着ます, while 切る (cut), also read きる, becomes 切ります. The identical reading makes it especially important to learn the meaning, kanji, and group together.
Use irregular forms and dictionary labels
する becomes します / しない. 来る, read くる in the dictionary form, becomes きます / こない. Its kanji can remain unchanged while its reading changes, so check the kana too.
Record each new verb's dictionary form, meaning, group, and masu-form together. Once its group is clear, the same verb becomes a reliable reference point when you learn further conjugations.
Check: Can you form 帰ます by simply removing る from 帰る?
Show the answer and why
No. 帰る is group 1, and its masu-form is 帰ります（かえります）. The final る alone does not make it a group 2 verb.