One step at a time
On the topic of training, I would really like to stress the importance of finding out what works best for you. If you have spent a little bit of time researching training methodology, you know that there is a ton of well-meaning advice out there, but it may not all work for you.
We are all a bit different, both in genetic make-up and more importantly, training background. So, some riders may respond very well to lots of high intensity training while others progress more with longer, easier sessions and a few hard efforts. How do you find out what works for you? Experiment. Don't be afraid to try out various things.
It's important that you have the guts to do something, even if there is a possibility for failure. Playing it safe all the time will not give the results you want. You have to have a "killer" mentality to certain degree, both in training and racing.
Dare to train hard, harder than you have before. Next time you do a TT, go out harder than you have - test your boundaries, find out what is too hard. If you haven't blown-up in a TT, chances are you are racing below your potential.