Play with cheaper fits? 20 Militia deaths is cheaper than 1 ADV death.

In otherwords, if you don't care about meaningless KDR's then ISK earning is easy.

It's a pretty good indicator of who afk'ed their way through 1.3

Play PC

Don't die.

I usually copy one of the basic militia fits so I get a couple of freebies, then plug in some goods that I want over the top. Most of my pay suits are between 2,000 - 5,000 ISK with the weapon of choice usually being most of the cost. Unless you're planning on plowing through people, basic shield extenders, and a simple armor repair can help when you get clipped.
Taking time on the field to look around and pick fights at a bit slower pace can also help to conserve money.

However, if you have a good squad, then the more expensive suits become a bit more viable for combat revenue because they allow better steamrolling of the competition.

It's a pretty good indicator of who afk'ed their way through 1.3

This

Get better.

You don't care about KDR? Cool. Use a starter assault suit and militia weapons and play ambush exclusively. The matches are rarely longer then eight or nine minutes, and you'll earn 120,000-169,000 isk per fight. You'll earn more if you get a lot of war points, obviously, but it really doesn't matter. I earned 17,000,0000 in a three day binge.

Don't spend it on tanks.

I got 170 mill ISK if it makes u feel any better ,and only play 3 times aweek

Like everyone else said, get milita fits. Skirm. Hack every objective that you can (you want to be in the top 5, if not top 3 to get the big payouts WPs gets you there). Pick your fights.

Or you can create an alt that's nothing but your cash cow. Or you can just transfer some money to your alt. Keep repeating the process and you should be good.

You should dedicate days to strictly ISK farming.

mmmmm i see plasma cannon and scramble what your k/d ?