Have you just moved into a house with a septic system when you've never dealt with a septic system before? If so, you're going to have to change how you treat disposal through flushing. Many items are supposedly flushable, either because they're small or because the manufacturer has called them flushable, but in reality, these items can ruin your septic tank. These are items you should throw out (if you aren't already).
Personal Hygiene Products
No matter what the boxes say about those wipes being flushable or tampons being flushable, they really aren't—especially if you have a septic system. Neither of these products fully dissolve and they can clog up the pipes and filters in your system. Given how quickly household members might go through some of those products, there comes the risk that you'll fill up the tank sooner than expected. That increases your septic maintenance costs because you'll have to have a company come out and empty the tank more often.
Septic systems contain bacteria that help break down the waste that goes into the tank. Just like any other bacteria, these bacteria are subject to destruction from antibiotics. If someone doesn't finish their prescription for some reason, flushing the remaining antibiotics down the drain could kill off the beneficial bacteria in your septic system. To dispose of unused drugs, contact local hospitals and the police department in your area to find out about drug drop-off programs.
Even if you take the antibiotics, they can still end up harming the bacteria in your septic tank once they pass through your body. Those antibiotics will keep working and can throw off the balance of good bacteria that keep your septic system in line. By all means, take antibiotics when you need them, but consider having your septic tank inspected after you've finished the course of medication.
Most people throw out dryer lint. But if you're one of those who flushes it (Inspectapedia notes that this does happen), stop. As with personal hygiene products, the lint can clog the system very quickly. Lint is also a devil to deal with—while it won't dissolve, it can break into bits. You can end up with multiple partial clogs that are growing and making your plumbing slow down.
If you want more advice on safely using the septic system, talk to septic maintenance companies about the problems they've seen at other homes. They want that tank and field to work just as much as you do, so they should be able to give you pointers. Septic tank service companies like Mr Bob may be able to help.