My personal method.

Find a system that has 2 level IV agents in the same station.

I have me in my Nightmare/Tengu/Nighthawk/Astarte(considering changing this up for a Talos) (mission dependant).
I have my alt in a very, very heavily tanked Dominx with Sentries, Heavies and remote Rep drones (shield/Armor dependant) with Remote armor or shield reps (mission/ship dependant on the above).

I then accept a total of 4 level IV missions.

I will blast through them... fast. A combination of high DPS main ship with a logistical Dominix with sentries makes for quick missioning. I rarely worry about aggro because of having all that tanking locally and remotely.

Once I complete those 4 missions, I will run back. Hand in all 4, then send out the alt, to salvage & loot all 4 missions.

Whilst I am doing this, I am running 2 level 4's with me at the same time. Usually, this will end at the same time as the salvaging, at which point I will make a judgement call on whether to loot & salvage those two, or just begin the cycle again.

I could just do the blitz of 4x4x4x4 all the way through, without looting, but I have a little manufacturing plan in mind for the future which I would like to try out...

As others have said, there is better and quicker ways to make money, but this works for me and keeps me engrossed. I like trying to multi task a lot, so... its fun.

My personal aim is to move onto a WH at some stage, as despite what I am doing being quite good, I want something new. The general opinion is a multipurpose dual box will make more money in a wormhole, from what I have read.

Take it easy.