I got 1 day, 10 hours and I'm second prestige level 16 right now.

Use Specialist to complete all the perk challenges, stick with one gun until you get 500 kills, play ground war. Try to use as many perks as possible, there is a ton of XP you can get by completing perk challenges.

A lot of ranking up fast is dependent on how good you do every match. I recomend demolition. At rank 60 each round you win you get a high match bonus, around 5k or so. and if you are defending and lose 1 bomb and still win you can get all the way to 7000 if you did good. guns i suggest low recoil high power ARs such as the scar-l or ACR. i choose silencer with extended mags on my scar-l and red dot and silencer on my acr.

perks i use.
Sleight of hand pro
Quickdraw pro
stalker pro

I use the support package with recon drone or sam turret, stealth bomber, and emp.

One of the easiest ways to rank up is to 1) Play with a FULL team 2) Play either TDM/Demo/Kill Confirmed 3) Use Specialist Strike Package 4) Use different weapons when you get a gun to around 25

This is what I have used to get to 1st prestige in 17hrs, I got a 60 win streak (and counting) by playing with my friends and my friends only; if my friends aren't on then I play campaign or spec ops. This can be annoying but trust me, this game is a lot easier when you are playing with a team.

Hope this helps