My greatest fear is to post a duplicate question here, how can I avoid that?
Even this very question here at meta might have already been asked, how can I have this vision to see the questions that have already been asked about a particular subject?
Are there more than one way? Can I use Google somehow?
My greatest fear is to post a duplicate question here
First of all, I would like to dispel you fear. Asking a duplicate is nothing to be ashamed of, nor something others will blame you for. It can and it will happen, and is not a negative thing, it simply means that the original wording was not the one you (or others) would have used, and having a duplicate will facilitate finding the question in the future.
This granted that you have at least tried to search.
how can I avoid that?
search for the tags you were planning to use: you can do this by visiting the tag page and clicking on the relevant tags.
or search similar words that could describe your question: you can do this by using the search box on the top right of the page.
In addition to what Federico mentioned, yes, you can use Google. In fact, at least from my experience, I'd say Google is generally better at searching SE than SE's search feature is. SE tends to rank pretty high in Google results, so just a normal Google search of what you're looking for is not unlikely to find it here. That said, you can also narrow your Google search to only look at our site.
For example, doing a Google search for:
site:aviation.stackexchange.com how can I search
will yield this question as the top result (or, at least it does right now.) :)
Also, to reiterate what other's have said, there's no inherent problem with duplicates. They will be closed as such, but, unlike other close reasons, that's not an indication that you've done anything wrong. If you search for the answer to your question and don't find the question here that already contains the answer, it's likely that someone else will eventually do the same thing. They will then find your closed duplicate question which will point them to the question that contains the answer. So, closed duplicate questions are still useful. We still want to close them, though, so that all of the answers to the question will be in one place, not scattered across several different questions. Also, it helps to prevent duplicate efforts to answer a question that has already been answered.
