If you don’t know Japanese grammatical particles, here’s a helpful list:
“o” indicates the direct object,
“wa” is the topic,
“ga” is the subject (the person/thing acting out something in the sentence, stronger emphasis than wa),
“kara” means from, since or because,
“ni” is the indirect object, adverb maker and means in/at and “to”( for passive verbs)
“de” means “via” and “to” (active verbs)
“e” means “to” (for directional verbs like iku (to go)),
“made” means “until”
“to” placed after nouns, means “and”
“mo” means also (or when placed after several things means “either, or” (positive verb) or “neither, nor” (negative verb))
“ya” means “such things as”
Step One: Types of verbs and their stems
There are two types of verbs, the first type, called ichidan, or first conjugation, end in (i)ru or (e)ru. The second type of verb, called yodan, or second conjugation, can end in gu, ku, bu, mu, u, su, tsu, ru and nu. To get the stem of a verb remove the endings previously indicated. To get the stem of a verbal adjective, take the last i off the end.
Step Two: Basic verb and verbal adjective conjugation
Verbs and verbal adjectives by themselves basically represent the present tense. For the first conjugation (i)ru and (e)ru becom ita and eta, respectively. For the second conjugation, gu becomes ida; ku becomes ita; bu, nu and mu become nda;ru, tsu and u become itta; su becomes shita.Keep in mind though that there are irregular verbs out there, such as suru (to do) which becomes shita (did), kuru (to come) which becomes kita (came) and iku (to go) which becomes itta (went).For the past tense of verbal adjectives, remove the last i and add katta.
To make the present negative tense, for the first conjugation take the verb stem and add nai. For the second conjugation take off the last vowel and add anai. For verbal adjectives, take off the last i and ad kunai.
Tip: When verbs are used just as they are for the predicate, the sentence has an informal tone. This informality is used with friends and family, or people you feel like being rude to (not reccomended!) To sound more polite, in situations where you don’t really know the person you’re talking to, it helps to learn the semi-formal conjugation.
Step Two: Remember these patterns: Stem of 1st conjugation verb + eba; stem of 2nd conjugation verb + reba; stem of a verbal adjective + kereba.
Step Three:Think of a verb, conjugate it into its stem and add the conditional particle. Add another sentence after that and you’ve got a conditional sentence!
An example of 1st conjugation: Benkyoo sureba, atama ga ii da = If you study, you will be smart.
An example of 2nd conjugation: Kawa o oyoreba, atama ga mizu o sawaru: If you swim in the river, your head will touch water.
An example of a verbal adjective: Sukaato ga akakereba, iranai: If the skirt is red, I won’t need it.