There are countless ways to get access to a system hacking in general is a very broad subject. There are new and diffrent vulnerabilities found every day some disclose there information others dont. Ever looked at zone-h and wonder how all the .br's are doing mass defacements ? the answer the holy grail to a novice hacker the 0day heh how hard is it to ./ ahh its more complex than that most of the time you just cant get any old exploit and run it against a host, sure it may be running the vulnerable version of software but the target architecture may be diffrent if its a buffer overflow and it was wrote to target a linux system it wont work on solaris because of the diffrent stacks but if you wrote it to brute force the return adress in theorey it would work against most linux systems. So how do all the .br's get a hold of the 0days simple they hang around IRC and eventually they will come across a 0day then they will go through a cycle of jumping from server to server looking for people to trade that 0day with for another 0day and so on untill they have a small arsenal then they will start going after hosting companys since the exploits are undisclosed they have quite a bit of freedom on the net people call them script kiddies etc but i would call them a novice hacker getting there feet wet i have flamed people calling then SK's and **** but the real defacers and **** know there stuff ven if they cant code and **** they still have a clue about what there doing dont worry this is leading some where . So what was that rant all about hehe my words to you is learn to code read about how overflows ocur and how you can take advatntage of them read up on XXS (cross site scripting) idefense has a good white paper learn about unicode attacks and directory traversal learn tcp/ip (tcp/ip isnt flawless it holds vulnerabilities ) learn about format string's (hmm not seen one in a while) still good to know though learn php and perl learn networking in general there was a post with a **** load of links to cisco papers all worth a read there are many more things that you could learn thats just off the top of my head (no i dont know all of that but i have goten the jist of most). If its possible set up a small test network with 3 to 5 puters
with diffrent operating systems and software and put up vulnerable applications on a computer and use various puplic exploits to try and brake in learn how the diffrent systems log incomming traffic packet sniff when you get in install rootkits to see what they do where they hide what method they use etc if you dont wont to learn all of the above learn to program its actually fun and rewarding when your tinkering with programs you have wrote have fun and keep it legal

NOTE in learning stuff a hands on aproach is good if you dont have the cash to set up a small network at the very least try and get another box or a good friend who would loan or be interested and willing to bring his box over to your house to "play" we dont want emails about stray packets now do we