First you will need hella lot of lockpicks, you can find them in shady places like the sewers, homes, pirate dens, caves, and all the shady business places. Also look in armories, barracks, and other military places. Basically, if it is breakable in these places and it looks like a storage holder, break it, and loot it.

You WILL come across guards, so be sure to level up your combat skills in the market in the Agora and any market at that, it is your vital part to the Raider plan.

Kill the guards to loot, steal, and break into places, and be sure to kill any witnesses. But do it fast and aggressively. Never allow long combat.

Kill anything and anyone that is a threat or aiding the threat and never allow alarms to be raised, no horn blowing.

Loot EVERYTHING. Chests, weapons, coins, treasure, ingredients, armor, armor upgrades, throwables, etc, everything is going into your inventory. Especially keys, levers, documents, and side mission items that will lead to more loot.

Always complete side missions, puzzles, and unlock any door with loot inside, in fact, unlock all doors.

The main quests can wait, remember money is the most vital resource to keep an army moving.

Never buy armor upgrades, only buy items that suit, support, and aid your playstyle.

And most importantly, NEVER hesitate to loot bodies, kill guarding animals, kill civilians, and/or kill running enemies/targets. You fight and kill for gold like a Raider.

Good luck, Know no fear, and Happy Raiding!