pretty self explanatory, just chose a character, it does not matter at all.

Press new --> Missions --> Olympus --> Go down a bit --> Press "Breachhead: recon" mission (first mission) --> select hard and hardcore for double rewards (bottom left) --> Claim prospect --> no items needed, no friends needed --> wait the 20-30 seconds it takes to load and land --> turn around immediately and leave using drop ship (return to station button) --> press the required buttons and wait the other 20-30 seconds --> rinse and repeat.

just select the first mission in olympus (breachhead: recon) with both hard and hardcore modifiers, then immediately leave.

the first mission is designed for new players, and so you dont need to do all the objectives. Pretty sure this also means that you dont need to do any of the objectives too, and just leaving is good enough for the game. 50 ren per run isnt great, but the only other guides i saw was for 200-250 per hour, so yeah.