Life into Phoenix
All monsters have a limited amount of experience to give. Each shot you are empty that experience pool.
One of the first steps when entering the Core is to have a clear objective. For example: you may want some extra equipment for your platoon, or maybe some components for weaponry/armour. As such, refer to the page "Scavenging The Core" for a definition of what you can expect in each zone in Phoenix.
If you plan on capturing zones, keep in mind that just one player will set off the Zone Control timer. It is always recommended that you are with at least two other players when capturing a zone. If you're a lone scavenger in a faction you will be running by a strict timer to collect everything that you need. Remember to use the sewers to stealthily visit each zone.
If you're still relatively a low-level player, it's always a good idea to take assignments. They will help prepare you for any combat you will get in the Zone, and will net you a fair amount of experience.
If you're a Sewer Rat (factionless), one thing to take note is that you will have no HQ to work with. Therefore, you have to think very carefully about the equipment you'll be carrying. Two weapons are recommended, and four is a maximum. You will also be walking target for all factions and even other factionless players if they're feeling particularly trigger-happy. Only disconnect when you're in the world map for extra caution. Remember however, you can still take missions from other factions on the outskirts of their respective HQs. As it stands, there is only the Awareness quest - try to complete that quest as soon as you can, as the perk will be a massive boon.