What helps is if one has a flight director. Then you fly the plane into the command bars and climb out, get the AP on (if you have one), and then retract gear/flaps as required. A Cessna 340 most likely had the equipment I described. You have to be current and proficient as an instrument pilot. You have to have a plan. What are you going to do if you lose an engine for instance. Most professional pilots plan on losing an engine on takeoff or at/after rotation, and mentally review the procedure before hand. That may be a cause of this crash, some type of mechanical problem, might not be. Could have had an engine failure at rotation. Who knows, but we'll probably find out the cause after the NTSB investigates.
This was a Part 91 takeoff, meaning one can takeoff in zero visibility conditions. Not the most wise thing to do, but legal. You wonder why the FAA doesn't require a minimum visibility for takeoff under Part 91 like there is for Part 135 & 121.
Part 135/121 (Air Taxi, airlines) will have required visibility for a particular runway at an airport. Example, might have been 1/2 mile for this runway.