How To Rank Up Particular Mods?

[KamaNightfire]

Hello everyone.

My question is what would be considered the most effective way to rank up Uncommon or Rare mods?

So far i'v only ranked up mods I could find doubles for to help level them, except rares which i'v been using Fusion Cores on instead, maybe throwing in a cheap or useless shotgun mod to boost it enough to it's next rank. What is the most effective way to rank up mods other than waiting and hoping you get several duplicates to rank up with?

Is it far more efficient to just use cheap or useless mods to rank up with at the cost of more Credits, since credits are by far the only material in this game that is truely expendable compared to other mods/materials or Platinum.

At this moment I want to hurry and rank up my Shields/Health on my warframe to max as fast as I can, as well as rank up my melee attack speed/charge speed, and waiting for 8+ or more of the same mod is a bit bothersome, especially when some of the mods labeled as " common " or otherwise are not as they appear.

Any helpful info would be great, thanks!

[mutex]

Maybe helps: http://warframe.wikia.com/wiki/Fusion