I learned more English grammar from my four years of Spanish than I did in English class.
GimB - the type of word ending in -ing is called a gerund. This is not a no-no, as it is an active verb, generally showing something happening at the moment, rather than done and completed. It is a way to describe an ongoing movement rather than something done once and completed. So, from examples:
"He walked to the store." By the time you finish reading the sentence, the subject (he) has already completed the action. He isn't doing the walking any more - he walked there, and now he's done. Whatever follows from there should be descriptive of what happened after he arrived.
"He was walking to the store..." This is an incomplete sentence, but notice that he was in the middle of walking - it was incomplete - when....something happened. What follows from there should indicate what happened while the subject (he) was performing the verb (walking).
"He had been walking to the store when..." It's a weak verb tense, because it's not providing any information that "He was walking to the store..." doesn't, but it uses an additional and unnecessary tense. It's useful in some other languages, but less so in English - and in any language, it's a weak tense. Training yourself to use past, present, or future tense completely will make your writing more vivid, stronger, and bring the reader into your world a little easier.
Not that I'm some huge authority on the subject, but that's what works for me, it's what I notice from the books I enjoy reading, and it's what I was taught as well.