Rule: The -ing participle, especially if it refers to something that is accomplished fact rather than something foreseen or imagined, is preferred as grammatical subject; as subject complement the infinitive is preferred.
Examples of errors:
The factors governing the choice of infinitive or participle are poorly understood. In some cases the two constructions are interchangeable; in cases where they are not interchangeable, the preference for one or the other may be partially idiomatic, and partially dependent on semantic and syntactic factors. For example, the infinitive seems to be preferred when it expresses a hypothetical concept, something which is predicted or imagined but not yet considered an accomplished fact. This would seem to explain the definite preference for the infinitive in (l)-(2), and for the -ing participle in (3). Compare also the following sentences, where the idea expressed by the non-finite clause is obviously hypothetical, and the infinitive is preferable:
His secret wish/desire/ambition is to marry Raquel Welch/*marrying Raquel Welch.
On the other hand, pastime is not very different from hobby (cf. (3)) in that both can express activities regarded as accomplished facts, and yet one can say either
My favorite pastime is to go/going for long walks in the woods.
with no discernible difference in meaning.
Cutting across these semantic considerations,, the syntactic function of the clause also seems to affect the choice of the infinitive or -ing participle. When the non-finite clause functions as subject of the sentence, for example, as opposed to subject complement, the -ing participle seems preferable. Compare:
The best way to catch cold is to go without/going without a coat.
If you want to reach him quickly, the best way is to telephone/telephoning.
*To go/Going without a coat is the best way to catch cold.
*To telephone/Telephoning is the best way to reach him quickly
When the non-finite clause functions as extraposed subject, however, the infinitive is usually preferred, as in (4)-(5). There can be a good deal of variation here too, though, e.g.:
It's nice to have/having money in the bank.
It wasn't nice to call/*calling your brother a jerk.
It's enough just to know/knowing you're here.
Do you think it's clever to make/*making a remark like that?
If the subject of the extraposed non-finite clause is expressed--i.e. introduced by for--only the infinitive is possible (cf. (6)).
In sum, there are a number of different syntactic and semantic factors that affect the choice of the infinitive or participle in noun clauses. All things considered there seem to be more restrictions on the -ing participle than on the infinitive--except in subject position, where the -ing participle occurs more frequently. As a rule of thumb, then, the learner may be well advised to use the -ing participle clause as subject and the infinitive elsewhere.