One » Use unexpected malts to add layers of complexity. I love the Gambrinus honey malt, as it gives a really nice sweet and nutty characteristic that adds complexity and balance to the roasty malts in stouts and porters. Weyermann’s Carafoam is another one—specifically Weyermann’s for the fruity and biscuit character it has to it. Cara Red is another one that’s not traditionally used because it just doesn’t have the SRM contribution to get you to that darker color, but it gives you a beautiful ruby hue if you don’t have a completely opaque stout or porter. It adds more raisin, dark cherry, and dark fruit notes along with some of that crystal caramel/toffee character. I usually pair them with a chocolate malt as the primary dark malt with a little bit of roast malt, typically in a 75–25 percentage of chocolate to roast. If I’m looking for a lighter body, I use debittered black malt (with the husk removed) so it doesn’t pull out as many tannins.
Two » Dial back your hops bitterness to compensate for the bitterness of the roast malt. Depending on the beer I’m brewing, I dial back my hops IBUs by 10–20 IBUs to compensate for the bitterness the roast malt adds.
Three » Keep esters under control. I want the malt to shine through and not have a strong yeast characteristic. Be careful not to ferment too hot or underpitch, or you’ll get more fruity characteristics. Taking cell counts is key to make sure you have a robust pitch that can handle your stout or porter.