Competition Sites:
1) ACM ICPC
2) codeforces
3) topcoder
4) codechef
5) google code jam
6) Saratov university [espl for tricky testcases]


To do:
===========
0) Study and practice
1)Always read a chapter from algorithm and do problems in book
2)Solve the related problems in contest sites
3)Solve the related problems available in all text books
4)Always choose hard problems and try to solve it...
5)Solve interview problems related with it
6) Read topcoder articles and solve problems related with it...



1) Trees
http://codeforces.com/problemset/tags/trees
2) Graphs
http://codeforces.com/problemset/tags/graphs

3) Datastructures
heaps,segment trees,BST, HashTable
http://codeforces.com/problemset/tags/data%20structures

4)Expression Parsing
http://codeforces.com/problemset/tags/expression%20parsing

5) Hashing
http://codeforces.com/problemset/tags/hashing

6) strings
http://codeforces.com/problemset/tags/strings

7) string suffix:
http://codeforces.com/problemset/tags/string%20suffix%20structeres


8) greedy
http://codeforces.com/problemset/tags/greedy
9) dynamic programming problems list:
http://codeforces.com/blog/entry/325
http://codeforces.com/problemset/tags/dp
10)Divide and conquer
http://codeforces.com/problemset/tags/divide%20and%20conquer


11) Mathematics
http://codeforces.com/problemset/tags/math
12)geometry
http://codeforces.com/problemset/tags/geometry
13) probablilities
http://codeforces.com/problemset/tags/probabilities

14) combinatorics
http://codeforces.com/problemset/tags/combinatorics

Above are from codeforces...
Below are from topcoder
15.Recursion
16.sorting
17.String manipulation/string parsing
18.Encryption and compression
19.advanced math
20. sortings..
21.maze
22.BackTracking
23.Maximum flow problem

Best resources for competition programming preparation:
http://problemclassifier.appspot.com/
http://emiraga.wikispaces.com/Problems+by+topics
https://github.com/BrockCSC/acm-icpc/wiki/Online-Resources
http://www.stanford.edu/class/cs97si/
http://webcourse.cs.technion.ac.il/234900/Spring2012/en/ho.html