We can’t really help you in getting more Impressions. Impressions are completely buyer-based. if someone sees your gig in search results or on a category page, you’ll be credited with an impression. There is nothing you can do to directly influence or gain more of this stat.
The only way to gain the potential of being seen more in searches is to have a great gig that people want, a gig that sells well, and a gig that earns great reviews from the work you deliver. Fiverr seems to like featuring these kinds of gigs within their search results, because these are the kind of gigs that earn money for Fiverr.
As far as the tags you should use, experiment – see what works. Keep what does work, and keep experimenting to find new ways to replace those that don’t.