1.
Prayer.
2a. Oil sampling, change oil/filter when needed. I'd take samples at ~3K miles, and at 3K--4K intervals after that until you see the oil starting to degrade. Depending on what the lab analysis finds, you may or may not need to make repairs as indicated. See recent oil analysis thread.
www.gmt400.com/threads/oil-analysis.59491/
So I shelled out $30.00 for a snapshot inside my 5.7, I know it is mostly useless unless it’s done over an extended period. But at the same time it does give an idea of current condition. Also did transmission fluid, which I’m curious to see, but that didn’t come in yet. Anyway, numbers look...
www.gmt400.com
in particular, post #36.
2b. Dump a 20-oz bottle of Techron Complete Fuel System Cleaner in the gas tank at every oil change.
2c. Buy "Top Tier" fuel. "Top Tier" fuel has additional detergent additives to keep injectors 'n' valves clean.
3.
Make sure the air/fuel ratio is maintained. Fresh O2 sensors, and the upgraded electronic fuel injection system should help.
4. Buy a scan tool, learn to use it. Check fuel trims, O2 voltage/crosscounts, misfire counts cylinder-by-cylinder. Verify ALL sensors, and computer outputs.
5.
Install a bypass oil filter in addition to the "normal" full-flow fuel filter. Requires a return fitting on valve cover, or preferably in the oil pan. The supply tee can go under the existing oil pressure sensor. (Supply is easier than return.) My experience has been with "Frantz" brand, but Amsoil sells their version, and there are others. I get 'em used on eBay. The Frantz filters use a roll of a_sswipe as the filter medium--cheap and effective.
6. Clean/effective radiator, along with proper coolant--not old/worn-out/depleted/electrolytic coolant. Flush the engine and PULL THE DRAIN PLUGS which may be a regular iron/steel plug on one side, and a knock sensor on the other side. The knock sensor has to be reinstalled with sealant and proper torque. Make sure the fan clutch engages, and the actual engine temperature is reasonable, using a stock-temperature 'stat. DO NOT drill holes in the thermostat.
7a. Effective air cleaner with quality filter. No holes in the air intake tubes. Don't waste time, money, effort, or enthusiasm on "hot-rod" "air intake kits". Any engine with a mass-air sensor probably should not have an oiled-gauze (K&N style) air filter. Overall, I'm not that thrilled with K&N filters anyway.
7b. Replace the fuel filter now 'n' then, too.
8. Fix any oil leaks.
9. Early Vortec engines had known problems with intake gaskets. Those faulty gaskets are probably all replaced by now, and the gaskets available currently are improved. It's worth replacing them, though, when the intake manifold comes apart to install the upgraded injectors.
10. Assure PCV system works properly.
Bonus: My service-replacement Caprice engine installed in my '88 K1500 went 19 years and 80K miles, failed due to head gasket problem that pounded cylinders 3 and, especially, 5. If the head gaskets had been replaced before the engine self-destructed, I'd still be driving it.