As per the official rules, you may draw a profession card when selecting an action in the third column and may play a profession card when selecing an action in the fourth column. I suggest a house rule which says that when selecting an action in the second column you may discard a profession card in order to draw a new profession card off of the top of the deck.
I have not tried this rule yet, but intend to at the earliest opportunity. With many cards being powerful, but *very* specific to a certain strategy and many of those being worth rather few points a limited ability to exchange cards would give an option to take poor cards out of your hand. In addition, this mechanic would closely follow the bonuses for the third and fourth columns and make it easy to remember. There is of course an argument that the game was not tuned and tested with this in mind and it could make the second column too powerful. However, I think the potential to more often find synergies in the card play might make this worthwhile as far as enjoyment.
I think I might like it in column 3 better. before drawing you can discard a card then draw 2. I think it would keep the "too powerful" down a bit.
Been using this variant for a few games now, works great for us. It still feels mostly 'as intended', while also giving a bit more leeway in case of unwanted draws. So thank you for the suggestion Steph!