No, you should think about "I help her" and you should remember that you need a preposition. Помагам means I help, not I give help.In the example above should you think in terms of "giving help to someone"?[/USER]
With pronouns, you use the dative case. But because nouns do not inflect for case, you use the preposition на to form a dative construction as in the example above.
Is there any difference in the meaning between the accusative and dative versions?
Yes. I think that in different contexts the dative construction is much more used than the accusative one, when we talk about the verb помага.It seems as if the dative construction has a greater chance of being "correct".