Hi Debbie,
I did this trip with just you a few years ago and loved it Although not my first it was just as enjoyable. Here is what I wrote then .....
"I did this trip last November and it was fantastic especially the Amazon add on. If you search through previous posts using the therm "Peru" you will find lots of tips including a link to photos of someone who had been previously.
The best advice I can give is drink lots and lots of water to avoid altitude effects and the coca tea (a bit like green tea) is free and available in all the hotels. we all felt it a bit but one man more than anyone else because he didn't drink enough. (there are always toilets nearby so the normal "see one use one" applies)
its very informal so you don't need lots of clothes but be prepared for cold due to the altitude. if you are doing the Amazon take a head torch rather than a normal one as you will need both hands. I prepared so much for the biting things on the first night but didn't bother much after that as didn't seem to be a problem. you can take walking boots but they get a bit muddy so wellington boot socks and wear the ones they provide. ............
Dont be nervous ( Iknow thats easy to say but you will be in good company seeing things that are amazing
Keith