TIP: Judges are evil and are out to get you.
This simply means that judges expect your output to conform exactly to their specifications. Since judging is done automatically, each character is expected to be in the right place. Input and Output specifications will be explained thoroughly in the problem statements and during the contest you can ask judges for clarifications via PC2 environment that will be used during the contest.
This also means that if judges say the input may go up to 1000 characters, there will be an input of 1000 characters. Some problems may have special cases that may not immediately apparent, such as certain boundary conditions. Judges may not tell you about those cases if they can be deduced from the problem definition. Do not assume anything. If not sure, ask the judges.
TIP: Easy problem that takes 1 hour to solve is the same as a hard
problem that takes 1 hour to solve
For the purposes of the contest you are judged on the time it takes you to solve a problem, not on how difficult a problem is to solve. You will do much better solving 2 easy problems in 1 hour than 1 hard problem in 1 hour.
TIP: Solve the problem that will take you the least time to solve
This is to improve your score. Let's say problem A will take you 40 minutes to solve and problem B will take you 20 minutes.
If you solve A, then B your score will be 40 + 60 (minute marks) = 100
If you solve B, then A, your score will be 20 + 60 (minute marks) = 80 (better score)
You thus want to solve the problem that takes you least amount of time to solve first. Leave problems that take longer for last.
TIP: Switch between problem as needed
It is easy to get stuck on a problem for a while. Sometimes when you get "wrong answer" it is also tempting to keep on working on it and trying to "get it". This can hurt you. You may do better by dropping that problem temporarily and solving another. At the end of the contest is it better to have one unsolved problem and one solved problem, rather than the single unsolved problem that you just can't get for whatever reason.
TIP: Write your code correctly the first time.
For some programmers debugging is the most time consuming part of writing a program. To compensate for this, it may help to visualize the problem first, so that you when you code, the coding becomes a simple translation process of your algorithm to code. One reason for slower coding times can be trying to solve the problem as you are writing it. Your attention is then split between thinking about the algorithm and coding itself. If in the middle of the problem you realize that your approach to solution is wrong, you have to spend time fixing and rewriting your code, when this could be avoided. The more details you know about your algorithm beforehand, the easier it is to code and your debugging time is minimized.
This should be enough information for you to process at this time.
Knowing and using these tips will give you an edge over contestants who don't know or don't use these tips.