You train it, it is pretty much the slowest skill in-game you I would suggest planting all the highest level seeds you can get hold of across the place, and somehow visit them all often.
I think Farming but it depends on what you enjoy doing
To be honest. Get off runescape and get a better life or play a Habbo. I'll answer your question anyway. search on Google: Sal's runescape and your question will be answered in more of a runescape way.
The total exp is 13,034,431 experience for a 99 stat on RuneScape.
There is a girl that has 99 on all skills her runescape name is 'xxphatmagexx'.
There are farming calculators out there, and depending on your level and what you will be using to level this skill up you can get the price of that item and times it by how many you require for this answer.
Farming,Slayer,Agility,and summoning EDIT. Summoning isn't supper hard but thanks. Runecrafting and Mining should be added to this list.
you train it
TRAIN
There are no cheats in RUneScape. Getting level 99 in ANYTHING requires a considerable effort.
you keep training your skill to get up to lvl 99
To get a skill cape you must get 99 in the one of the following skills Attack:99 Strength:99 Defence:99 Magic:99 Range:99 Prayer:99 Constitution:99 Mining:99 Smithing:99 Herblore:99 Agility:99 Slayer:99 Farming:99 Hunter:99 Construction:99 Summoning:99 Crafting:99 Thieving:99 Firemaking:99 Fishing:99 Cooking:99 Runecrafting:99 Dungeonearing:99 or true skill mastery:120. Hope this helped :)
Fish Salmon & Trout in shilo village to 99.