its not going international
google ranking is dependant on high quality content in good quantities.
also google ranking in say UK will be different to ZIM, this is because local only sites will gain higher rankings on the local google, this is because the formula takes into account that a local result is more often a better result
if no better local result exists it then falls back to global data (i'm not sure how it does this or how it defines global data, i'm also not sure how it localises websites other than by domain e.g. co.zw)
basically if there was a techzim UK site with uk specific data then that site will always rank above the techzim zim site on the UK google site, but in zim, the techzim zim site will always rank higher than the UK version - thats obviously assuming that both sites rank well for specific terms in the first place
the simplest answer is making sure your content is not spammy, doesnt contain spam comments and isn't duplicated on other domains and that your content is of a good length (not too long though - they tend to rank long content lower because of other unknown factors in there ranking algorithms), get the basics like that right combined with the right META keywords and descriptions and your well on your way