Lithuanian doesn't have the wide variety of tenses as, say, English or French. There are only 4 tenses (2 of them are past), some moods and a few participles. So one good news is that you probably won't get lost in the number of tenses as you would in English.

Lithuanian has three main verb forms. Using these three forms, you can make everything else: tenses, moods, participles, etc. So it's the most necessary to know those three main forms for every Lithuanian verb. When learning, try to memorize them all, instead of just the infinitive.

The three main forms are as follows: infinitive; present tense third person; past tense third person. For example: pykti, pyksta, pyko (to be angry, he/she is angry, he/she was angry). So when you learn, you'll have to learn all three 'girdėti, girdi, girdėjo' (to hear, he/she hears, he/she heard) by heart.

Alongside that, you'll have to recognize which conjugation a verb belongs to. The number of conjugations is three. Which conjugation a verb belongs to is determined by the second main form (present tense third person). This is a very important form, because depending on what the ending of that form is (either -a, -i or -o) you can easily recognize the conjugation. Let's illustrate it with the following table:

I have made the endings of the present verbs bold, because, as said, they determine the conjugation of a certain verb. For example, dirbti belongs to conjugation 1, because its second form ends in a. The ending of stebėti second form is i (stebi), therefore the conjugation is 2. And finally, rašyti second form is rašo, thereby it is a verb of conjugation 3.

If you don't find yourself puzzled after all these paragraphs, you may move on to explore the three conjugations. As you saw in the table, every conjugation has different endings, so it is very important to recognize the conjugation number.

All in all, when you are learning new verbs, you should memorize their three main forms and the conjugation that the verb belongs to. You won't need anything else, because everything else comes from these.