Bounty hunter
Dangerous for: Different levels for different arena
Location: Level 20 mid of wilderness
Why: Do you want to die instantly in a place and lose all your stuff? While this is the place, Bounty hunter is one of the most dangerous places in RuneScape, you will find most players have higher combat level than you and start attack you nearly instant after you enter the arena, so never bring anything to this minigame unless you are a very high level and know what you are doing, if you want to have some protection and bring your armor, don't ever go far from the gate, I did and lost lots of Rune items that worth 700K or more.
Stronghold Security
Dangerous for: Level 3 - 50
Location: Barbarian Village:
Why: What's one thing that you don't want do but want do at the same time? Going to the Stronghold Security, attack by aggressive level 80 ghosts and then reach your destination and get reward of either Rainbow boots or Fighting boots and 10K coins, this place is just slightly safer than Bounty hunters since you still have your gravestone, but always remember, bring some food with you if you are a low level and if you are almost ran out of food and health, go into a gate and teleport to Lumbridge, because you can always go back to the level you were in with the portal.
Wilderness
Dangerous for: All the levels
Location: >level 20 in the wilderness
Why: What's the most dangerous aggressive NPC in F2P? Good guess, it's Revenants, not only they can unlimited heal and can attack used all attack styles, they can also freeze you and than attack you, from level 7 imp revenants to level 105 Ork revenants, they are dangerous to all the players. If you ever caught by a revenants, always remember, Run is the best way to escape.
Karamja Volcano
Dangerous for: level 3 - 50
Location: Under the Volcano in Karamja
Why: Remember Lesser Demon? The aggressive monster you fought in Dragon slayer? They are back again in Karamja, but this time, there are more than one of them and will attack you, so don't go there unless you are high enough, again, the dragon Elvarg is also in there for you to slay, but remember to bring anti-dragon shield and leather armor for more magic defence bonus!!
Al Kharid Mine and Falador underground Mine
Dangerous for: level 3 - 20
Location: Al Kharid desert and Falador Mine
Why: Scorpions in these locations definitely look hungry, they will eat players of any level, if you ever seen one, remember, again, run is the best choice if you don't have enough power to fight with them.
Most expensive items
Most expensive armors
Combat
Full set of Saradomin
Cost (GE): 3955651 coins
Obtained: Treasure trail (Members only)
Introduction: A treasure trail award only members can obtain, this is currently the most expensive armor in Runescape although it gives the same stats as normal Rune armor.
Ranged
Full set of Green d'hide (g)
Cost (GE): 589108 coins
Obtained: Treasure trail (Members only)
Introduction: Another treasure trail award, this set has no Green d'hide coif (g) since it came out after the set was made, the set gives the same stat as Green d'hide set.
Magic
Full set of Blue wizard (g)
Cost (GE): 1146713coins
Obtained: Treasure trail (Members only)
Introduction: Blue wizard (g) full set gives the same bonus as blue wizard which cost 70 times less expensive, people usually used it as a sign of wealth in F2P.
Most expensive bow
Willow composite bow
Cost (GE): 59910 coins
Obtained: Treasure trail (Members only)
Introduction: Willow composite bow gives same bonus as willow bow and can only use arrows up to Mithril, it's another treasure trail present and is the most expensive but not the best bow a F2P player can get.
Most expensive weapon:
Rune 2H sword
Cost (GE): 39522 coins
Obtained: Made by smithing skill with Rune bars, smithing level required.
Introduction: 2H sword is the slowest Rune weapon but it gives the best stats, a person can't wield it with a shield since its 2 handed.
Most expensive Rune
Death Rune
Cost (GE): 303 coins
Obtained: Made by Runecrafting skill, only members can make this kind of Rune
Introduction: Death Runes are used for medium level strikes, the best attack strike a nonmember can do, it's the most expensive Rune in F2P.
Most expensive food
Swordfish
Cost (GE): 461 coins (Raw), 388 coins (Cooked)
Obtained: Harpoon fishing with a fishing level of 50 or above
Introduction: Swordfishes are the best fish a nonmember can get, it heals 14 hitpoints each with cooked ones and requires a cooking level of 45 to cook it.
Most expensive gloves
Rune gauntlets
Cost (GE): 72906 coins (Worn-out)
Obtained: Fist of Guthix minigame reward shop
Introduction: This is one of the best armors a nonmember can get, it costs 200 FOG coins to buy from the reward shop inside the Fist of Guthix arena, it will degrade if you die and go back to Lumbridge and cost you 35 FOG coins to recharge.
Most expensive amulet
Strength Amulet (t)
Cost (GE): 473358 coins
Obtained: Treasure trail (members only)
Introduction: Strength Amulet (t) gives the same bonus with Amulet of Strength but with a different appearance, it's the most expensive amulet a F2P player can wield.