Battery tips, and power usage from battery versus cable

Any tips for making sure the battery on my laptop will last for ages before needing a swap?

Also, is there a way in settings that I can make my Mac use power from the cable and not battery when it reaches 80%? And then I can force it to reach 100% if I'll be going out after and I know I'll need all my battery. If it's not native to macOS is there a good third party app that would help with this? Preferably free but if I have to I can pay for it to. Thanks!!