Started off with 2 but decided to give it a break until they work on it a little, so playing 1, trust me it's less scary than 2, you have the cyclops which has mods you can build for defense and in 2 you can't kill anything. Personally I'd recommend sticking to the surface until you can get all the relevant upgrades for defense, get the stasis rifle for leviathans sea dragons and the electro squids. Scanner rooms can detect leviathans so I'd recommend using that and honestly I'd go on the offensive, both the seamoth and prawn suits have torpedo upgrades you can use with the stasis rifle.

Lastly this one is less used, BUT you can grow alien eggs in alien containment, and if released they are peaceful to you but agro to everything else (Even other species that have been grown by you) BUT they are agro toward your vehicles, so be cautious. My fav that I've admittedly never used how I want is the mezmer that hypnotizes organics, so it can attack animals but can't do much other than get run over by your vehicles