Thinking of taking my girlfriend to paris advice?

just wondering if you have any general advice on hotels good but not to expensive as it is rather low budget im only we are only 16 although i will be saving for about a year or so. just wondering about good hotels located near the main POI's as well as restaurant recommendations. also its the first time i will ever be abroad alone so i was wondering apart from flights and hotels what other costs should i expect to pay for or things should i book? finally how much should i bring for food if we are staying there for 7 days? any other points about things to do places to go would be awesome :) thanks guys :D