My intention here isn't so much to detail technique or scheme, but to advocate for planning out your philosophy of what you are going to have your defensive line do. People do any number of crazy things with their schemes and I really do believe that whatever works well for you is what you should be doing, but at the end of the day you'd better fall into one of these categories: Slanting defense who also plays shades, shade defense who also slants, or a two gapping defense who also slants. My intention is to explain why these are the primary philosophies you should be employing and what benefit I think these give you.
Slanting With Shades
Slanting is a popular base technique for the defensive line because of two main reasons: 1-It's easy to teach the technique and 2-Slanting will allow you to play a different kind of athlete on the defensive line than you might normally do. You can put a third string full back on the defensive line and slant him and give him a chance to not only play, but to succeed. Slanting is also something that you can take a kid who's slow to coaching and let him rep it and figure it out to a greater degree than he might be able to in comparison to shade or two gapping (although I think two gapping does have a certain simplicity to it).
Pairing slanting with shade technique is important for the same reasons that a junkball pitcher needs to throw his fastball, lousy though it may be. If you're constantly slanting and moving on the defensive line, the offensive linemen will get used to the idea soon enough and will start expecting the man in front of them to be slanting left or right. When you change that to coming off the ball and playing a shade, it's like a fastball that coming unexpected when all you've been looking at are change ups and curve balls. That 89 mph fastball isn't much, but it's much more effective when the batter isn't looking for it. This lets you make a sub-par player better by giving him the advantage the offense normally has: HE knows where he's going.
Shade With Slants
I like playing shade techniques, I think if you're going to base in a reading front, you should be playing shades most've the time. Playing a shade is a great thing because your kids only need to control half of a man, which is a winnable battle most of the time. The specific technique used is up to individual coaches, I'm of the Pete Jenkins philosophy of defensive line play that declares the most important thing is the hips and hands, followed by the feet, but to each his own.
Continuing the baseball analogy, if slanting is throwing junk balls, then shade with slants is throwing fastballs with an occasional slider. You're turning the game from a guessing game or battle of smarts into a bit more of a execution based match up, where you can get it done or you can't. I'm not saying that shade technique is a boom or bust approach, but I do think that it is more execution based than slanting.
What I like about pairing shades with slanting is that, much like throwing a killer slider takes advantage of your great fastball, by slanting on important downs or unexpected moments you can get a whiff of sorts, where the OL misses his block because it's not happening where it has been the last four or five times.
Two Gapping With Slants
Two gapping is an interesting technique. It is very polarizing amongst the coaching community, most folks will say that you require some kind of Vince Wolfork or Casey Hampton type in order to make it work. I disagree. I think you can get it done with an athlete who can be quick off the ball and play with great leverage, hips and hands. I didn't say much about size or strength there because, from what I've learned of the technique, it's secondary to their get off and their technical ability. Mike Patterson of the Philadelphia Eagles is not a giant of a man, nor is he a weight room savage, however he executes a two gap technique regularly because of his get off and his hands.
Now, as far as pairing two gapping with slants: two gapping is a very aggressive, competitive, downright imposing style. Slanting is the yin to that yang. You go from hitting the offensive linemen in the chest and beating them in the direction they want to go to hauling off and going straight to a gap, which is drastically different in approach, attitude, and responsibility. Switching my analogy to boxing, two gapping is working the body and then slanting to occasionally go for the head. You can soften them up and then choose your moments when you've got them leaning, using that to score big points.
But We Do Something Different!
Good on you! I've never said this is how everyone should be, I'm just advocating my person thoughts. But I think you'd be hard pressed to find better complements within your defensive line play than the three outlined here.