If you don't have an extra laptop or even if you do, follow the mentioned instructions but do all your finanical and banking transactions booting into a USB stick with the TOR operating system installed on it. It's has fully encrypted partitions, your connection is anonymous and it automatically wipes your RAM writing over it with random 1s and 0s when you shut it down.
You could do the same yourself if you make a separate enctypted patition on your computer and install a Linux OS in it. You can easily wipe your ram before you leave.