Making Money can be separated into two categories, collecting resources and processing resources.
Tips on collecting resources
Respawn time: The respawn time for a tree, rock, monster - anything is determined by the amount of people on a world. For example, Iron ore on a world with 1500 people will take less time to respawn than Iron ore on a world with 500 people.
Player Density: Better respawn times are great, but if there are too many players around chopping the same tree or mining the same ore, you should consider hopping worlds. If someone hops into your world and takes your spot, the best thing to do is just world hop. What do you care more about - money making or beating a loser?
Use Teleports: If you can use magic to get to your resource location or monster location the use it. Runes are cheap compared to the time saved teleporting.
Don't wear heavy items: Your full trimmed rune armor or outfit may look cool, but your run energy will decrease faster. Runescape has some pretty good looking standard outfits. Learn to love them for their 0 kg weight.
Tips on fighting boredom
Have friends: Friends are a big part of what makes runescape great, giving you something to do while socializing. If you don't have friends then get friends. If you are shy you need to put yourself out there and find some friends.
Watch Videos: Youtube is your friend. While woodcutting, try watching an entertaining video or perhaps learn something from one. Videos are a great way to give your mind a break from Runescape's monotony.
Listen to Music: All of you music lovers out there can groove to your favorite tunes when playing runescape. Skilling to the beat of a song can be a fun alternative to your normal skilling.
Take a break: Breaks during Runescape are a good way to keep the game fresh and new. Perhaps watch a TV show every now and again then come back to Runescape to continue skilling.
Play Minigames: Minigames, or activities as now called by Jagex, are fun little distractions from the main activities of the game. You play a game of Castle wars, Clan wars, Blast furnace, Fist of Guthix - anything every now and again. These minigames have some good rewards for playing too.