Planning a trip is best done with one of the many travel guides available. I like the Lonely Planet guidebooks very much but others, such as The Rough Guide or the SouthAmerican Handbook are also excellent. The guidebook will be your best friend on the road, lots of useful information about travel (transport, accommodation, food, etc...) and practical issues.
It's not a bad idea to have a room reserved in a hostel before you arrive in Lima. This will save you the trouble of having to shop for one when you arrive (this can be quite hectic). Get local currency at the airport and take a taxi to your hostel, that's it. You can check out some hostels on the
South America hotels section of our website.