I saw on Codeforces on regular basis ,that there are a lot of questions and answers about practicing and practicing more.
Although It is my opinion that the Educations Rounds are best for this, at least for people like me. They learns from it and the problems are very nice and intersesting.
So I've collected the links for all the educations rounds that has happened.
Educational Round 1 : http://mirror.codeforces.com/contest/598
Educational Round 2 : http://mirror.codeforces.com/contest/600
Educational Round 3 : http://mirror.codeforces.com/contest/609
Educational Round 4 : http://mirror.codeforces.com/contest/612
Educational Round 5 : http://mirror.codeforces.com/contest/616
Educational Round 6 : http://mirror.codeforces.com/contest/620
Educational Round 7 : http://mirror.codeforces.com/contest/622
Educational Round 8 : http://mirror.codeforces.com/contest/628
Educational Round 9 : http://mirror.codeforces.com/contest/630
Educational Round 10 : http://mirror.codeforces.com/contest/632
Educational Round 11 : http://mirror.codeforces.com/contest/652
Educational Round 12 : http://mirror.codeforces.com/contest/660
Educational Round 13 : http://mirror.codeforces.com/contest/665
Educational Round 14 : http://mirror.codeforces.com/contest/678
Educational Round 15 : http://mirror.codeforces.com/contest/691
Educational Round 16 : http://mirror.codeforces.com/contest/702
Educational Round 17 : http://mirror.codeforces.com/contest/710
Educational Round 18 : http://mirror.codeforces.com/contest/762
Educational Round 19 : http://mirror.codeforces.com/contest/792
Educational Round 20 : http://mirror.codeforces.com/contest/797
Educational Round 21 : http://mirror.codeforces.com/contest/803
Educational Round 22 : http://mirror.codeforces.com/contest/808
Educational Round 23 : http://mirror.codeforces.com/contest/813
Educational Round 24 : http://mirror.codeforces.com/contest/817
Educational Round 25 : http://mirror.codeforces.com/contest/818
Educational Round 26 : http://mirror.codeforces.com/contest/825
Educational Round 27 : http://mirror.codeforces.com/contest/837
Educational Round 28 : http://mirror.codeforces.com/contest/845
Educational Round 29 : http://mirror.codeforces.com/contest/846
Educational Round 30 : http://mirror.codeforces.com/contest/863
Educational Round 31 : http://mirror.codeforces.com/contest/873
Educational Round 32 : http://mirror.codeforces.com/contest/884
Educational Round 33 : http://mirror.codeforces.com/contest/888
Educational Round 34 : http://mirror.codeforces.com/contest/893
Educational Round 35 : http://mirror.codeforces.com/contest/903
Educational Round 36 : http://mirror.codeforces.com/contest/911
Educational Round 37 : http://mirror.codeforces.com/contest/915
Educational Round 38 : http://mirror.codeforces.com/contest/920
Educational Round 39 : http://mirror.codeforces.com/contest/938
Educational Round 40 : http://mirror.codeforces.com/contest/946
Educational Round 41 : http://mirror.codeforces.com/contest/954
Educational Round 42 : http://mirror.codeforces.com/contest/961
Educational Round 43 : http://mirror.codeforces.com/contest/962
Educational Round 44 : http://mirror.codeforces.com/contest/976
Educational Round 45 : http://mirror.codeforces.com/contest/985
Educational Round 46 : http://mirror.codeforces.com/contest/990
Educational Round 47 : http://mirror.codeforces.com/contest/1000
Educational Round 48 : http://mirror.codeforces.com/contest/1009
Educational Round 49 : http://mirror.codeforces.com/contest/1016
Educational Round 50 : http://mirror.codeforces.com/contest/1027
Educational Round 51 : http://mirror.codeforces.com/contest/1036
Educational Round 52 : http://mirror.codeforces.com/contest/1051
Educational Round 53 : http://mirror.codeforces.com/contest/1065
Educational Round 54 : http://mirror.codeforces.com/contest/1073
Educational Round 55 : http://mirror.codeforces.com/contest/1076
Educational Round 56 : http://mirror.codeforces.com/contest/1082
Educational Round 57 : http://mirror.codeforces.com/contest/1093
Educational Round 58 : http://mirror.codeforces.com/contest/1096
Educational Round 59 : http://mirror.codeforces.com/contest/1101
Educational Round 60 : http://mirror.codeforces.com/contest/1107
Educational Round 61 : http://mirror.codeforces.com/contest/1117
Educational Round 62 : http://mirror.codeforces.com/contest/1132
Educational Round 63 : http://mirror.codeforces.com/contest/1140
Educational Round 64 : http://mirror.codeforces.com/contest/1155
Educational Round 65 : http://mirror.codeforces.com/contest/1156
