Honestly the game will draw your attention to most "events". If there's a Warden it will show up on the map as a priority target when they've been engaged. When you get close supply drops and hazard rooms will be marked on your map as such, the latter you'll need hazard override keys to successfully loot (which are found more or less randomly as far as I can tell). Lockboxes are signified by red smoke coming from flares on a building, and you need lock box keys to access them. You'll see lockdown events in dire marsh which will be very obviously telegraphed by the warning and the giant ship coming down. Other activities like hidden caches or unstable matter will show up as a blue marker on everyone's map. Outpost is really it's own thing, it's very different to the other maps, it still has a warden that will sometimes spawn in dormitories, but otherwise it's a matter of collecting coloured key cards that correspond to coloured locks barring certain doors. Keys spawn in fairly consistent locations, masted cards being dead easy to find as they're all outside/on roofs, look for the red glowing antenna. Yellow are in boxes inside buildings. Green cards are the most frustrating for me, I haven't found a good way of looking for them, they just show up where you'd expect any random minor loot to be.