"I enjoy to swim" is wrong. "I want swimming" is wrong. There is no rule that predicts which verbs take which — but the lists are short enough to learn.
Verbs followed by -ing
enjoy, avoid, finish, mind, suggest, consider, practise, imagine, keep, miss, admit
- "I enjoy reading."
- "She avoided answering the question."
- "Do you mind waiting?"
Verbs followed by to + verb
want, need, decide, hope, plan, promise, agree, refuse, learn, offer, manage
- "I want to leave."
- "They decided to postpone it."
- "He managed to finish on time."
Verbs that take both, same meaning
begin, start, continue, like, love, hate, prefer
- "It started raining." = "It started to rain."
Verbs that take both, different meaning
This is the part worth real attention.
- "I stopped smoking." (quit the habit) vs "I stopped to smoke." (paused in order to smoke)
- "I remember locking the door." (I have the memory) vs "Remember to lock the door." (do not forget)
- "I tried calling him." (I called, as an experiment) vs "I tried to call him." (I attempted, possibly failing)
After prepositions, always -ing
- "Thank you for helping."
- "I'm interested in learning more."
- "She's good at explaining things."
Watch out for "look forward to" — the to here is a preposition, so it takes -ing: "I look forward to hearing from you."
That last one appears in almost every professional email, and "look forward to hear from you" is one of the most common written errors.