This is not a guide to doing a single exploit, but rather, a few notes from my own experience from multiple games for finding those exploits we all know and love.
So, you don't have any technical knowledge or programming ability, and you don't think you can find out anything of worth. Wrong! Abusing a game doesn't depend on your technical knowledge or ability. The easiest way to find exploits is to let the game developers tell you about them.
How do you get them to do that? Simple. Just go to the customer service forum at their official website.
People are allways QQing about some bug or another that has ruined their gameplay or caused them to lag and die, et cetera. As an example from Diablo II:
HOW COEM EVRY TIME SUM NUB NECRO JOINS I GET LAG? WTF BLIZZARD FIX THIS I GET LIEK 2000 PING
Seeing that, it isn't a huge leap to the realization that you can use a necromancer's skills to cause lag and use that lag to dupe.
Here is an example from WoW Customer Service boards: WoW Forums -> WoW Crashing when I alt-tab into wow
If this guy were smart he would check to see if maybe his character got rolled back in the bargain. If it did, that crashing he complains about would be his ticket to undetectable duping and the insane ability to reroll prospects and other variable result crafting.
Another tip I have to offer is to push the limits of things. Sometimes, if a system recieves a value that is very small or very large it isn't prepared to handle it. Strange things can happen, just keep your eyes open for the unexpected.
Final tip: Always dig around to find out what functions are handled client-side. These things can be edited and abused, even seemingly minor things like default frames of animation can be changed around to your advantage.
Anyways, this isn't a guide so I am going to cut it short. Feel free to add your comments, maybe there could be a single thread for advice on finding exploits.