EDH Deckbrewing Help

I've designed this guide in a way that doesn't force anything down your throat. No specific card mentioning, let alone suggestions, for example. Many commander players want an idea of what to do, but prefer not to be told how to do it. My goal here isn't to push you towards building decks like mine, or anyone else's for that matter, but to aim you in the right direction. How you get there is your prerogative.

I have five concepts to outline:

Speed, Power, Resilience, Guard, & Interaction. The better you balance these five concepts, the better your deck will be.

Speed

The Speed of your deck is simply how fast your deck either gets its wincons together or deals enough damage to eliminate all other players on average.

It doesn't matter if that involves building a big boardstate, combo'ing off, generating enough mana for a bomb, accumulated damage, commander damage, infect, etc. How many turns it takes to eliminate your opponent's is your deck's speed.

The key factors determining your deck's speed are mana-curve, ramp, cost-efficiency, draw & deck manipulation (Such as scry and tutors).

Combo's aided by ramp tend to be the best way to a fast win whereas accumulated damage tends to be the slowest. A deck that can do both though, can be even faster or more powerful, which leads to the next part.

Power 

The power of your deck is how strong your wincons are and how consistently you can pull them off. Cards that declare you the winner (Or your opponent's loser's) are very powerful, except for how hard they are to pull off. Accumulated damage from many different sources is typically weak, except that it can be deployed as early as turn 1. There is also a difference in how these wincons hold up to interaction and that's where the next concept comes in.

Resilience

Your deck's resilience is how well it holds up to interaction, whether it be in the form of removal, counter spells, discard, etc.

Voltron commanders tend to be vulnerable to sacrifice and removal in general. This is because voltron decks don't typically "go wide". A good way to shrink this weak spot in a voltron deck is to put in cards that can pump out creatures, namely token creators. That way, you have fodder to sacrifice, not to mention chump-blockers if you need them.

Decks that lean too heavily into their commander are vulnerable to interaction as well. Although some commanders naturally pull most of the weight, some attempt should be made for a deck to be able to hold its own without its commander.

There are countless ways to up your deck's resilience. Cards that have or can give pieces evasion like ward, indestructible, regenerate, protection, or hexproof or phase out. There is also nothing like counter spells for stopping your opponents from stopping you.

One very overlooked factor in a deck's resilience can be land ramp. Whenever a mass-removal happens, such as a boardwipe, it's the person with the most lands that can typically bounce back fastest.

Guard

Your deck's guard is how well it holds up to aggressive creatures.

Decks sometimes focus on less boardstate that does more, but the price they pay for it is that they are weaker to aggression, particularly early on. Decks like this can have a weak guard.

A good way to improve a weak guard (Besides the obvious "Build a better creature boardstate") are cards that prevent all combat damage, boardwipes, and creature removal in general. Life-gain can help too, but is best as a "side-effect" that naturally occurs, rather than something to lean into.

Interaction

I saved the most obvious for last. I don't think most Magic players need to be told what interaction is or that they should have it. However, I do think most players underestimate just how much is necessary or optimal.

Keep in mind that interaction isn't just something to hit your opponent over the head with. The best players know that the best way to handle interaction is your own interaction. For instance: counter their counter or removal spell or boardwipe, or instant spells that can give evasion to cards or players your opponent's are targeting.

That said, any deck running blue should be running at least a few counter spells. I think that unconditional counter spells printed at two mana-value (Let alone the free-spells) was a balancing mistake. To have access to blue and not run them is just about guaranteed to be a sub-optimal decision.

To Conclude

If you are wanting to up your commander game, simply try to gauge where your deck sits in all of these five categories to find its weak-points. Then consider ways that you can improve your deck in that area, ideally without sacrificing much in other areas.