Choosing what deck to play is one of the most difficult aspects of preparing for any tournament. That said, you can make this decision easier on yourself, and achieve more success, by avoiding the most common pitfalls. Here are 10 mistakes you shouldn't make while choosing your 75 (or 95, if you're playing Yorion, Sky Nomad).
This article is directed toward competitive players looking to level up their game. If your primary goal is to have fun with the cards you already own, or to make specific plays, choose whatever deck is most fun for you! But if you have fun by doing your very best to win, read on.
This is huge. I hear many stories about players who feel obligated to play a certain deck because they hear about how great it is from other players. Trusting other people's opinions over your own can quickly lead to frustration.
Play to your strengths. If a deck isn't putting up the results you want it to, don't play it, even if you know other people are doing well with it. This could be due to you not playing it perfectly, but that's okay. Not everyone is going to be equally good with the same types of decks.
This leads me to my next point. It's extremely important to learn what types of decks you are good at playing. Even at the highest levels of competitive Magic, plenty of players succeed by choosing decks based on their preferred playstyle. Take a look at Greg Orange, who only plays control decks. This is okay. Not only does he know he's going to play a control deck for every single event, but by focusing on only one section of decks, he's better able to utilize his preparation time.
Many players don't have the time or resources to test every single deck they could possibly play. Focusing on one type of deck allows you to narrow down your options earlier in the selection process. This often will leave you more time to test and refine whatever deck you do end up playing.
Time management is an incredibly important part of preparing for an event. You don't want to make a deck decision too late, nor do you want to make it too early. I am speaking from the perspective of someone who often waits until deck registration deadlines to fully lock in a list.
However, even if I don't finalize my list until the last minute, it is very likely that I have been tuning whatever deck I do submit for quite a while. I often have tuned versions of a couple different decks at the end of my testing process, but I also have enough time to play Magic for many hours before events, and chances are you don't have the same luxury. The key is not to lock down your list before you have a good idea of how to sideboard with it. Only then can you be sure that all 75 cards are what you want them to be.
Most players realize the danger of making a deck choice at the last minute, but it's also not a good idea to make your deck choice too early. The metagame can change very quickly. A deck that was good a week or two ago isn't necessarily going to be as good the next week. I like to be playing up until the final hour for this reason.
Making an educated deck choice is impossible if you don't understand what the metagame looks like. If you practice online like me, there is a very good chance that the popular decks online will show up in whatever tournament you are preparing for. Of course, you will often run into unexpected decks as well, but that's natural.
One of my better deck choices was when I brought Simic Flash to Mythic Championship VII. I didn't think Simic Flash was amazing, but I chose it because I wanted to be able to beat Jeskai Fires, the deck I thought would be the most popular. This turned out to be accurate. Soon after Mythic Championship VII Simic Flash wasn't in as great a place, because the metagame shifted. For that particular tournament though, it was a great choice.
This is a very important point. Don't feel like a deck is so good that you are obligated to play it. Remember Oko Standard? I was trying to beat Oko, Thief of Crowns, not play it, even though the card and deck were completely busted. That deck wasn't my style, and that's okay. Especially in so-called solved formats, it is easy to peg what the best deck is, so that is the first thing you should be testing against. I rarely play the best deck.
Not everyone has time to do targeted testing against friends or teammates, but if you do, you absolutely should. The first matchups that you want to play are the ones you expect to be the most popular at the event you are preparing for. Don't start with a brew or a pet deck, as that is an easy way to get sidetracked. Also, play sideboard games. You need to play enough games to really get a feel for how the matchups play out.
Ever heard of winning both sides of a matchup? This is where skill comes in. Sometimes players are going to have positive win rates with most decks, which is a testament to simply being a strong player. However, you should be careful when you claim that your deck has a good matchup against another deck. I often heard players claim about how good a matchup they had against Mono-Red Aggro, and then I would beat them.
This is part of why targeted testing is so important. Say I jump onto the ladder and play some matches and win most of them, but my opponents make some mistakes. It is hard to quantify exactly how the mistakes my opponents made impacted the results. Then I show up to the tournament, and a matchup I thought was positive actually isn't. This is an easy trap to run into. Don't trust what the matchup looks like on paper, or from a couple ladder matches.
In order to really gather enough data from playing online, you should make a spreadsheet and track how every match goes. Also, it's a good idea to timestamp the matches. Lists change from week to week, so your matchup and sideboard plans need to change with the metagame.
When it's time to make your final deck choice, the data you've collected from all your matches will prove invaluable.
Due to time constraints, many players rely primarily on what they have read on the internet to make their deck choice. This is perfectly fine for a casual tournament, but not the greatest idea if you want to be fully prepared. Unfortunately, not everything you read on the internet is good information.
Watching a stream, reading a sideboard guide or following a post on Twitter will only get you so far. In an ideal world, all this information will just supplement your own ideas and preparation. I'm not saying all of this information is bad, but go to sources you trust, and remember that information changes quickly, just like metagames. If you are looking for something like a sideboard guide, it needs to be current in order to be accurate. If you feel comfortable doing so, make adaptations to decks you see or read about as you prepare. Copying and pasting someone else's 75 rarely works out.
This last point is one that is very important to me. The testing process shouldn't feel like homework, or you aren't going to want to do it. If you pick up a deck and simply don't like playing it, then drop it. This doesn't have to be about data.
For me, I almost always do better with a deck I actually want to play. That means I'm going to be excited to play the deck as often as possible. Without that excitement, this whole process goes out the window, because you will lose your motivation. You can't rely on winning to make it all worth it—we are talking about a game that involves a lot of luck, after all.