Past participles of most of the weak verbs are formed as follows:
ge + stem + t as in gemaakt
ge + stem + d as in gewoond

-t is added to stems ending in p, t, k, s, f, ch.
infinitive (stem) → past participle
hopen (hoop) → gehoopt
praten (praat) → gepraat
koken (kook) → gekookt
missen (mis) → gemist
blaffen (blaf) → geblaft
kuchen (kuch) → gekucht

In Di3M they offer to memorize  p, t, k, s, g, ch using the mnemonic of ‘t kofschip.
However, I find it easier to memorize the mnemonic offered by dutchgrammar.com
which is pocket fish 🙂

Spelling note: Doubled consonants never appear in the end of the Dutch words, so if a stem already ends in “t”, no extra -t should be added. See “praten → gepraat” in the list above.

All the other weak verbs add -d to the stem:
horen (hoor) → gehoord
bellen (bel) → gebeld
branden (brand) → gebrand

Spelling note: a second -d should not be added if a stem ends in “d”.
See “branden → gebrand”.

Weak verbs which have prefixes be-, er-, ge-, her-, ont- and ver- do not form their past participles with the prefix ge-. These verbs are called inseparable, and their prefixes are also called inseparable. However, either -d or -t is still added in the end of a stem:
bedoelen (bedoel) → bedoeld

n case if a stem ends in “d” or “t” the past participle matches the stem in spelling:
verbranden (verbrand) → verbrand

pocket fish rule doesn’t work with the verbs which have a “v” or a “z” in infinitive and the stem ending in -f or -s. In these cases -d should be used to form the past participle and not -t:
geloven (geloof) → geloofd
verhuizen (verguis) → verhuisd