The default is the most crucial strategy to de_inferno.  It's the base of every other strategy and it's your anti-aggro in the beginning of every round.  For Counter-Terrorists, an aggressive play style is really effective versus teams that don't have an organized default, so putting a stop to that early on sets a very important precedent for the remainder of the half.  Once you have the CT's playing defensively, it will allow you to do fakes and creep up real close before executing.  All of this relies on your default.

The most important part of any strat, is putting the right players in the right spots to make sure they are as effective as possible.  If the default isn't working out after a few scrims, you should adjust your players positions because no matter how right someone may seem for a certain position, or how bad they want to play a certain position, it just might not be the right one for them.

The Anti-Aggro

Setting up the anti-aggro in the beginning of the round is as important as the strat itself.  If you can't prevent agressive pushes and random peeks, you'll never have the chance to get setup to execute your strat. We've all been there and we've all seen it first hand. If you're playing aggressive in the beginning of a match and you keep getting shut down, you'll stop pushing completely.  You'll be afraid to peek and you'll play defensive the entire half, until you start getting the confidence to push again.

When I first made it to CAL-Invite with Confederacy, I remember playing a match versus CyberGlobe on de_inferno.  We were one of the most active invite level teams and we spent hours each night practicing tons of different strats and come match time we didn't get to use any of them.  Every round CyberGlobe would do an aggro, smoking and flashing alternate middle and randomly peeking us, while their B players naded and pushed out B. We started every round down atleast one or two players, and never got the chance to execute because of all the random peeking.  I remember trying to justify it to myself, by saying they would never be doing this if we were wearing a different tag like "u5" or any other top team at the time.  They were showing us no respect at all.  We ended up losing the match something horrendous like 16-3.

It's been years since then and by now I realize the importance of the anti-aggro on de_inferno.  If you give a team a reason not to respect you, and give them no fear of pushing against you, you're giving them a huge mental edge.  If you shut down that aggro early on, you'll force them to play your game, and play defensively so you can get as close to a bombsite as possible before you execute, taking the bombsite with ease.

Taking over Middle

Generally, I would put my awper and my strat caller in these two positions. I do this for a few reasons.. In most cases, your strat caller is more reliable to follow a standard and not play in a fashion that's going to get them picked.  It also allows for your strat caller to be in a better position to call which site to execute on, as they have a view of both sites from middle. It also prevents your awper from getting pushed on and if he's needed at middle, he can easily run up mid to make a pick at A.