I’ve looked into a few different language-learning methods (on the internet, audio CDs and in several classrooms in junior high and high school), and one thing I noticed about language lessons geared toward people with no foreign language experience is that two thirds of the time they initially skip out on verb conjugations, so I’ll start with that in the present tense. First person singular (“I” in English, “ich” in German) takes -e at the end of a verb instead of ending in the infinitive -en, e.g. “springen” becomes “springe”. Second person informal singular (“you” in English, “du” in German) takes -st instead, e.g. “springen” becomes “springst”. Third person singulat (“he, she, it” in English, “er, sie, es” in German) takes -t. First person plural (“we” in English, “wir” in German) has the -en ending like the infinitive form of the verb “springen”. Second person plural (“you guys” or “all of you” in English, “ihr” in German) takes -t like third person singular. Third person plural (“they” in English, “sie” in German) takes -en like first person plural, as does the formal version of “you”, which is “Sie” with a capital “S”. Notice that there are three sie’s: one means “she” and takes -t, one means “they” and takes -en, and the last one (used to address someone formally until you’ve known them long enough to use the informal form, like addressing someone as “Sir” or “Ma’am” in English – although it’s worth mentioning that children are addressed informally even when you first meet them) has a capital “S” and takes -en. When I was in school they taught us a song to help us remember how to conjugate our present tense verbs. It’s sung to the tune of “Mary Had a Little Lamb” and goes like this: “ich” takes “e” and “du” “st” / “er, es, sie” / “t” all three / “wir” “en” and “ihr” takes “t” / “sie” and “Sie” “en”.
There are multiple kinds of past tense verb conjugations. The simple past tense has no helping verb, and the way the verb is conjugated depends on whether it is a strong or weak verb. The weak verbs follow the same pattern as the present tense except with an added “t”. This is the result: “ich” -> -te, “du” -> -test, “er, es, sie” -> -te, “wir” -> -ten, “ihr” -> -tet, “sie” and “Sie” -> -ten. Notice that the first and third person forms are the same. The strong verbs don’t follow the present tense ending pattern and change stems, e.g. the stem “spring” becomes “sprang”. The first person singular and third person singular have no ending (so “sprang” stays as “sprang”), and for the rest of the endings one need simply add the present tense ending to the changed stem, e.g. “du springst” becomes “du sprangst”. There are seven classes of strong verbs as well as a class of irregular verbs, a class of mixed verbs, and the list of modal verbs. I’ll come back to those another time, but they’re important to memorize so you know how to change the stem when using the simple past tense.
The Perfekt past tense uses a helping verb (either “haben” or “sein”). “Haben” is the more common of the two in the perfect past tense, while “sein” is used to indicate movement or a change of state/condition. The “full verb” (not the helping verb) goes to the end of the sentence, and the helping verb takes the second grammatical position. Example: “Ich bin nach da schon gefahren” in which “bin” is the helping verb in the second grammatical position. (This is different from the simple past tense, which keeps the verb in the second grammatical position like the present tense as in the sentences, “Ich gab dir die Welt. Du wolltest sie nicht…”) The helping verb is the one that’s conjugated. The perfect past tense does three things to “full verbs” depending on whether they’re strong, weak, or mixed. The strong verbs have a “ge”, then a stem change, and end in “en” (e.g. “gegangen”). The weak verbs have no stem changes in the participle, so they start with a “ge”, then have the stem of the verb, and end in “t” (e.g. “gespielt”). The mixed verbs start with “ge” and end with “t” and may or may not have a stem change. When a verb has a separable prefix, it is connected to the verb before the “ge” (for example, to say “depart” or “drive off” the separable prefix ab- is added before “fahren”, so in the perfect past tense “he has already departed” becomes “er ist schon abgefahren”, whereas in the present tense the separable prefix goes at the end of the sentence independent of the verb). Here’s a list of some separable prefixes: ab-, an-, auf-, aus-, ein- and vor-. There are also inseparable prefixes. These have no ge- prefix in the perfect past tense, so it’s just the inseparable prefix before the stem regardless of whether the stem changes or stays the same. Here is a list of inseparable prefixes: be-, ent-, er-, ge-, ver-, zer- and miss-. A few prefixes can be either separable or inseparable. It changes depending on the meaning of the verb, so do your best to memorize any exceptions such as this that you find.