Layers are a must although the 7kg weight limit is difficult to stick to. However when you see the porters and how much they carry, you understand why the limit is 7kg. Good waterproofs as we had some rain are a must as is a good warm sleeping bag as it got cold at night on the trek.
Take a walking pole or two. We are so pleased we did in the end as they are a god send. Expect a lot of steps. Especially on day two. The walk is tough at points but stick to the pace of your guide and you will be fine.
We didn't suffer too badly with altitude sickness but we did take Ibuprofen regularly throughout the trip to stave off any symptoms. Also a water reservoir is much better than a water bottle as you can sip constantly which stops you stop starting alot on the up bits.
We loved the hot springs at the end of the final day, as the feeling of hot water on your skin was amazing. (We also turned them into a Brits abroad holiday as we all had beers and were quite loud, very funny).
Take something warm for the flight just in case the overnight flight is cold, like ours was and pack some spare clothes, toothbrush, baby wipes etc. in you hand luggage as the travelling is quite long.
Enjoy every minute, as like I am now, you'll miss being on the trek so much.
Book it now. Exodus have planned a fantastic trip and it's well worth the money. Although my only criticism is that all of the zips on our tents and the toilet tent did not work properly, which was very frustrating. Apart from that, there are no complaints from me.
I turned 30 the day we went into Machu Picchu for the tour (you don't need to go at dawn, too many other people go then, go around 7am when we did, it's perfect). I also got engaged that day, so thank you Exodus and Marcial for making my birthday so unforgettable.