ALCADIUS

Best answer as chosen by Asker / Ratings
Maybe you should see some videos. Try youtube.
One of my secrets is too collect the time limit when only 20 seconds are left. This means that if you get 90 seconds don't waste some 30 seconds searching for the other time bonus but start shooting. Also try headshots but becareful cause the parasite can grow from the baddies.

cheating-is-good

Here is a small secret that I use every time I play Mercenary. Right at the start of the level, when the timer first goes off, I run around the level, and I collect all the hourglasses. This means that I have the maximum time limit that I can have. Now, you see, what this does, is cut out the need for you to run around frantically looking for an hourglass later on. I used this tactic so I can focus only on killing the Ganados and other creatures that I encounter. I guarantee you that this will work better than if you start killing first. Also, if you use my strategy, all the Ganados will be a ways behind you, so you can just turn around and start killing. You will make a chain very quickly, and start racking up points like there is no tomorrow. This what I did in order to get the Handcannon, and Five stars on every level. Hope this helps.