How to sell more on microstock? The right way is good keywording.

When i started contributing on microstock, i didn't care alot about keywording. After the first
short period when i submitted everything i had, i started to pay attention to the type of
photos which had been downloaded the most, and i tried to adapt it to my portfolio, however
it is difficult. Of course i also tried to improve the technical quality of my pictures. I had
never payed attention to the keywording of my pictures, i just added the necessary
minimum as i didn't want to 'loose time' by editing detailed keywords to my pictures, as i
found it pretty boring. With the time i realised how important this issue is. I started to do the
exact opposite and added as many keywords as i could to my pictures, because i thought
the more keywords will add, the more times my pictures will appear among search results and
the more times they will be downloaded. However sometimes my picture got refused for not
having relevant keywording - for example on IStockphoto (www.istockphoto.com) there is a
strong control of keyowrds added to pictures, as keywords have to match their own vocabulary.
Some agencies also have a system which allows all users of the wesite to report the bad
keywording and also allows 'punishing' photographers who are adding irrelevant keywords for
example 'Dreamstime' (www.dreamstime.com).
Dreamstime also has a great function which shows which keywords sold the picture. I realised
that adding too many keywords will not help to sell the image because when a picture appears
in search results and is not relevant for the search, it will not be downloaded anyway.
So now i try to find the best way to add relevant keywords to my picture without having to
spend hours on there. Recently i came across the microsite 'Pixmac' (www.pixmac.com),
which offers its contributers professional keywording for free. This sounds good but i have not
yet tried it and cannot say if the keywording is good quality, however it is the only site offering
photographers free keywording. It is also still possible to keyword your photos by yourself but you
have to use their keywording guide which is based on clicking on the keywords and it helps you
not to forget anything. But what i found most interesting are systems allowing easy keywording
and multiple picture sending to different microsites. It is a payed service as far as i know, so i
have not yet tried it, but i definately want to try it as it seems very clever to me.
-The most interesting i found are www.findphotokeywords.com, http://photokeyword.com
or http://www.prostockmaster.com