When do We Use Gerunds or To Infinitive ?

We use gerunds (verb + ing):

• After certain verbs - I enjoy singing
• After prepositions - I drank a cup of coffee before leaving
• As the subject or object of a sentence - Swimming is good exercise

Here are some of the most common verbs that are usually followed by the gerund:

enjoy	I enjoyed living in France
fancy	I fancy seeing a film tonight
discuss	We discussed going on holiday together
dislike	I dislike waiting for buses
finish	We've finished preparing for the meeting
mind	I don't mind coming early
suggest	He suggested staying at the Grand Hotel
recommend	They recommended meeting earlier
keep	He kept working, although he felt ill
avoid	She avoided talking to her boss

We use 'to' + infinitive:

• After certain verbs - We decided to leave
• After many adjectives - It's difficult to get up early
• To show purpose - I came to London to study English

We use the bare infinitive (the infinitive without 'to'):

• After modal verbs - I can meet you at six o'clock
• After 'let', 'make' and (sometimes) 'help' - The teacher let us leave early
• After some verbs of perception (see, watch, hear, notice, feel, sense) - I watched her walk away
• After expressions with 'why' - why go out the night before an exam?

And here are some common verbs followed by 'to' and the infinitive:

agree	She agreed to give a presentation at the meeting
ask*	I asked to leave early / I asked him to leave early
decide	We decided to go out for dinner
help*	He helped to clean the kitchen / he helped his flatmate to clean the kitchen
plan	She plans to buy a new flat next year
hope	I hope to pass the exam
learn	They are learning to sing
want*	I want to come to the party / I want him to come to the party
would like*	I would like to see her tonight / I would like you to see her tonight
promise	We promised not to be late

*We can use an object before the infinitive with these verbs.

Source:

http://www.perfect-english-grammar.com/gerunds-and-infinitives-verbs-1.html