All that said, yes there are some things you can do to optimize viewing of your set, with or without calibration, which incidentally is not covered under any warranty I have ever seen.
However, I have performed calibrations under warranty on a couple of special occasions. More about that later.
Run your contrast at half for normal viewing, no higher. Max contrast, called Torch Mode, is deleterious to the health of your set and the efficacy of your picture. It blurs the focusing - called blooming - it pushes your grayscale out of linear operating range, on sets that don't have very good power supplies it tows the red and green images away from each other horizontally JUST on the brighter scenes, and it prematurely ages your phosphors. It also makes screenburn much more likely to happen, over time.
Run your color and tint for the best fleshtones, on an average of your channels. Redo it whenever necessary. ABC often sets up their HD programming with super hot color intensity, requiring that you reduce your color level. Where you run your contrast affects where your color level will land, and contrast affects brightness levels. Everything in there affects everything else, it's like a giant hanging mobile. Which is why the recentering part of a calibration is so important. It sets your centerpoints for all those things, so you will always have a reference to come back to. This reference point will be a direct replica of what was sent out from the director, and will be perfect for most video material, 99% of the time. One exception is Jay Leno's Tonight Show, where I always lower my brightness by 5 clicks (out of possible 63), maintaining the proper "clamping to black" that I desire in my viewing.
Remember that the blue isolation/filter test first originated in Joe Kane's A Video Standard laserdisc is ONLY good on LINEAR color decoding projectors. You can trust a ceiling pj to respond properly, but not a Mit RPTV, which has tons of red push. The blue isolation test is worthless on a red pushed scenario.
At that point fleshtones will get you your best pic, because it prioritizes them, which is the best way to achieve suspension of disbelief, which is the bottom line we are all trying to achieve. Only on a LINEAR color decoder will the color and tint be set perfectly via the blue isolation test, in which case fleshtones will then appear completely natural. Realigning color decoding is a strong, essential part of what I offer in my cals.
When you reduce or increase your color level, often you have to tweak your tint one way or the other to compensate. Calibrations reset your centerpoint on such things, but changing program material can always affect that.
Run your brightness settings to just be able to make out detail in dark areas, no higher. Significantly higher and you will fill in the dark areas too much, resulting in haze over everything. Brightness must be set on 2 different types of pic - one where there is darkness everywhere on the screen, the other where there are significantly bright areas of picture in some places, while at the same time there are dark areas as well. On superbright scenes where the entire screen is bright, altering the brightness control won't do much, so only set it with dark material up there.
Run your sharpness settings for just a little bit of edge enhancement, but not much. EE is great for DVs where you are sitting across the room from them, or RPTVs where you are again sitting very far away from them. The closer you want to sit from your RPTV, the less EE you are going to want, because EE blurs detail. Looks great from a distance, compromises your crispness when up close. On HD, my sharpness control on my Panny does nothing at all. It is completely disabled on HD, produces absolutely no visible changes whether max'd or min'd.
Sharpness bargraphs typically look best in the middle, because that's where they are typically most out of circuit. There's 2 types of sharpness - video detail softening on the left side, and edge enhancement on the right side. The first is for schlocky cable channels/signals that are weak and as such way too grainy, the second is edge enhancement. Middle is usually best, tho the newer Tosh's need to be more like 35% than their older settings of 50%.
Convergence is best done on a thin, medium light level grid, like AVIA's Letterbox Enhanced Circlehatch grid. Always do it on the actual picture you're watching ultimately, don't trust the crosshairs or any crosshatch grid from inside your set, as it is the actual picture you want to look best. Use those other things strictly for reference, but come back to the pic itself for the final pass.
Much of this, and more, is contained in the emailout I send to those who inquire about my services.