I've always organized my travels alone online. 

I would like to leave you some useful information to organize your travel, by booking your flight, hotel reservation, maps of the city, the subway maps and bus and tour to follow during the duration of the trip. 

First of all if you want cheap you have to choose the right dates. The cheapest flights are more during the week (I just booked a flight to Copenhagen paying 66 euro). Having traveled only in Europe I can tell you that one of the best companies is EasyJet.com. This company can also display the dates close to your date that you have sceltom to book the best opportunity. 

Always pay by credit card rechargeable (I use the Mastercard) and never with American Express, I had big problems to Barcelona and Amsterdam. 

As for the hotel I have always been happy with HostelClub.com and Viaggiare.it. Looking for a hotel in the center so you do not have to use public transport, you will save money and visit every corner of the city. Another recommended site is AirBnb.com, I booked the stay for Copenhagen ... then I will let you know. 

Before leaving, check the foreign currency if it is different from your exchanged a bit of money in your country, so you do not get there without a penny in his pocket. It happened to me in Budapest in the evening, and the change point were closed. A nightmare. 

Always start with a map of the city where you go, you can create on Google Maps routes between various points, for example from the station to your hotel. 

Make a plan of places to visit .. even if you do not follow him. 

Check the identity card, if it is not worth the stamp.