Know your max altitudes for the sectors and familiarise yourself with landmarks for altitude changes & turning points.
If you are using GPS, make sure your chart is efficiently folded incase your GPS fails. If flying single pilot make sure you have the reporting points, altitudes on a kneeboard. Also, I found is useful when first flying the heliroutes to make an A4 size copy of the route I was taking. Trying to work your way through the chart single pilot is a pain.
As with most things in heli flying, plan it as best as you can and it should be enjoyable. I started with the route H9, H10, H4 Northwood to Isle of Dogs. There are good landmarks for turning points so make nav a bit easier and you can get used to the radio calls, and possibly holding over the river. If you start to go too far off course - ATC will not hesitate to tell you !!
good luck & have fun.