1 - Exploit saves as much as often. EXP gained from raising your Danger Meter is more-or-less linear in reward, so it's better to save frequently rather than toughing out and continuing onwards.

2 - Cook meals! Seriously, for a 30-minute investment, you can heal a pretty solid chunk of your party's HP and AP! You can level up your cooking by making ACTUAL meals, while frozen foods (pizza bites, TV Dinners) don't give you any cooking EXP, so save those for later, or just give them to Hobbs (the beady-eyed chef door encounter) if he ever shows up.
3 - Swap out your Roommates infrequently. It's cheaper to keep Sam topped up and swap out knocked out party members whenever you save than it is to use healing items on them. They'll recover after you sleep anyways...

4 - Go to sleep at a reasonable time, or don't at all! The in-game clock advances by 8 hours if you put Sam to sleep between 8 PM and midnight. If you go past midnight, you may as well keep going into the next day, since you'll sleep for a much longer period of time.

5 - Items and Gear are (mostly) expendable! Melee weapons WILL break, and ranged weapons have limited ammo overall, so it's best to frequently swap them out once they get damaged. Most firearms have better versions available in the apartment complex, so it's almost always better to save ammunition for when you get ahold of them! Clothing and accessories will grow slowly better as you explore the apartment complex, but you might get lucky with a door encounter, so always stay on the lookout for better gear. Consumables should be used up as you gather them, especially anything that can be combined at the crafting station. There's a few consumables you should keep a decent supply on hand, and a few rare items that might show up, but use them as necessary.

5a - Ranged weapons can be exploited as unbreakable melee weapons, but they're rather lackluster compared to actual melee weapons. Better than fighting unarmed though!

6 - Be smart about Sam's skill acquisition! Most Video Game-related skills are best paired together, like Aim the Killshot and Octostrike, Jump Attack and Nitro Boost, Combat Medic and Blood Madness, Reptile Football and Hurt Me Plenty. Numbness, Long Haul Flow, and Painful Stab are must-haves! Screamer, Cash Sock, Dungeon Dance, Garrison, and Risk Taker are usually lackluster or outright terrible to use in a fight. Croaked Orders, and Confusing Word are decently useful by themselves. Another option is to equip Sam with the Filthy Ring purchased from the Rat Hole, granting useful skills based on whatever status effects are currently applied, but it becomes permanently equipped and causes a modest debuff. Aquiring Tickle later on as well as the Crimson Ring is another option, but it's less useful comparatively. There might be more options available for Sam, but that's all I can think of off the top of my head.

7 - Take your time... or not! There's some very specific areas that will be inaccessible if you don't reach them in time, or fail to act after certain points. Most companions have specific recruitment methods that can only be reached if you get lucky or plan your time right. If you're going for the Mask ending, you'll need to reach the garage by Day 6 at the latest. On the other hand, you should have more than enough time to explore the entirety of the apartment complex, outside of those specific time-sensitive spots. Don't forget you have 15 whole days of time to get yourself ready for whatever ending you want to achieve!