you can use verb+ ing(gerund) or to+verb (infinitive) inter changeable for most cases. However there are some verbs that requires gerund
for example Please stop
reading.
you can not say peale stop to read.
again you have to say, I forgot
to do this.
You can not say I forgot doing this.
the following verb and verb phrases require gerund
admit
appreciate
avoid
can not help
consider
deny
enjoy
finish
keep
pronspone
practise
stop
suggest
be accustomed to
be interested in
be opposed to
be used to
decide on
get through
keep on
look forward to
plan on
put off
think about
think of
Again the folling verbs require infinitive
agree
care
decide
deserve
fail
forbid
forget
hope
intend
learn
mean
offer
plan
pretend
refuse
I hope it helps you.