Every army has its strength, even the Necrons, they also have there weaknesses, even the IG. Each new codex has countless geeks, myself included, scouring them for the strengths. They then put together the best army they can to beat the current trend in Army lists.
The old army's don't reread their own codexes looking for a way to beat the new they throw out the same list and try their luck. The problem is that the new codex/IG player has read his book thinking about your army and has put together a way to beat it. He is fighting the next war and you are still fighting the last.
This is what the US did in Vietnam.
The IG are beatable but it takes a thinker to beat them. If you are only starting to figure out how to beat them as they setup across the table from you, good luck.
You need to look at your list and think about what you might face and build to fight it. This is hard, it is much easier to copy the crowd who have figured out how to win with the new codex, than it is to be original and think for yourself.
There is a reason that very few Generals names are remembered throughout history. It is not easy.
How do you take a fresh look at your own army? Throw out what you are doing. Look at ways to beat the current trend. For Mech we spammed Melta now what? Once you have an Idea go back to your list and make it work. You will find units that were once useless they might now have a value. If nothing else they will be something unfamiliar for your opponents. The challenge before all us non-Gaurd Players right now is not our codexes it is our own nature. It is time to overcome our own habits and change not to a new codex but to a new style of play. What will work. I don't know but I am going to look for it and I am going to find something that is new to cause these copy cat list to have to think for themselves. Something I know most will not be able to do.
The Guard are strong because everyone has spent points on a powerful weapon with an effective range of 6 inches (Melta). Time to change.
40k is not a game where the same tactic is going to win over and over again. If it worked last month it is most likely not going to work the next. Tactics can over come everything even bad dice.