The most important thing to remember is to just not die, learn to avoid getting into fights you can't win, learn to stay out of situation you can't escape from.
Some roles are easier to play against bots then others, also keep the enemy team in mind when building your items.
Playing a tank and building lots of health/resist/armor is a very easy way to win your lane, dominate team fights, and protect your base against the bots. Sejuani is fun and easy to play as a tank.
Or you can try a ADC and build a ton of damage/attack speed/critical and completely destroy everything that dares to come close. Tristana is a lot of fun to play and very easy to win with against bots, its also easy to escape bad situation due to her jump and ult.
(I've had a game where I played a Tristana and build the following items: Phantom Dancer, Infinity Edge, Runaan's Hurricane and Blood Thirster . I could just camp at their nexus even with all towers still up and just farm penta's. I ended up with 49 kills that game, it was just silly. It won't always work, sometimes bots just get scared and all 5 will just refuse to leave the shop area just because you are standing there all alone. XD)
This is all stuff that works against bots, don't do these things against human players.
EDIT:
You can also fuck around with the team compositions. Giving the enemy bots only champions that deal magic damage and then building a lot of resist items makes for a very easy game. The opposite also works give the enemy only champions that primarily deal normal damage and building armor items.
Or give them only champions of one type, like an all ADC composition, they will have a hard time getting enough gold to be meaningful in fights and will be easy to kill all game.
You can also give them champions with little or no CC making for far easier team fights later on.
You can also make things harder on yourself as well by giving your team a terrible composition and the enemy team a good one. The more weird stuff you try out the better a grasp of the game you'll get.
PS: Staying alive is important due to how bots reacts when they face a towers. Bots are very hesitant to walk in range of towers when a enemy champion is nearby, so if you can keep yourself from dieing then no mater how low your HP or your tower HP gets the dumb AI will most likely still back off even though you have no realistic way of defending it. This is also way it is important to focus on minions when defending, bots do not approach towers without minions. Having the Teleport summoner skill is also very useful so you can come to the aid of any tower at any time.