That's a tricky question. Actually you don't know. Therefore you always find the verb tables where you are offered the different stem-forms
infinite of the verb, (3rd person singular in present tense), 3rd person imperfect and perfect participle.
They are meant to be learnt by heart, and then you'll find also the other forms easily. Nevertheless there might be some help in the following

If you don't know the imperfect, you don't know whether it's a strong or a weak verb.

Example   schwimmen = to swim     There are two possibilities to say he swam.*     Er schwimmte or Er schwamm

* here you see (probably not for the first time) that the English perfect participle gives often (but by far not always) a good hint on the right solution.

The right form is Er schwamm. With this we know that it's a strong verb with changes in the vowel. Most strong verbs have changes of vowel in all the forms. We still don't actually know which one will be the right vowel in the perfect participle. It is geschwommen.

to swim       schwimmen - schwamm - geschwommen       ich schwamm du schwammst er schwamm wir schwammen ihr schwammt sie schwammen   This verb has the change in the vowel only in imperfect (the present forms ich schwimme, du schwimmst, er schwimmt, wir schwimmen, ihr schwimmt, sie schwimmen is not effected)

to open       öffnen = öffnete = geöffnet     ich öffnete du öffnetest er öffnete wir öffneten ihr öffnetet sie öffneten   This verb has no change in the vowel in imperfect; it is a weak verb. So we know the perfect participle will most likely not have a change in the vowel.

to drive       fahren = fuhr = gefahren     ich fuhr du fuhrst er/sie/es fuhr wir fuhren ihr fuhrt sie fuhren   This verb has a change in the vowel in imperfect and seems to be a strong verb; still there is no change in the vowel in participle perfect. s... happens.

to write       schreiben = schrieb = geschrieben     ich schrieb du schriebst er/sie/es schrieb wir schrieben ihr schriebt sie schrieben   This verb has a change in the vowel in imperfect; this means it is a strong verb and it also has (even the same) change in the perfect participle.

to bring       bringen = brachte = gebracht       ich brachte du brachtest er/sie/es brachte wir brachten ihr brachtet sie brachten   This verb has a change in the vowel in imperfect; this means it is a strong verb and it also has (even the same) change in the perfect participle.