Taxis are a good way of getting around in Slovenia, however in major tourist areas (Bled, Ljubljana) some can and will rip off foreign tourists. A journey from Ljubljana airport should cost approximately 40 Euros(some taxies from Bled area), however it is not uncommon for the charge to be 50 and more Euros. Before using any taxi ask for a price prior to using the service. This way you will help  to ensure you get a good deal.
Check the taxi prices to major tourist areas of Slovenia.

Never hire a taxi on Ljubljana railroad station or standing in front of hotels since the most expensive rate / km will be charged to you.  Instead call and order one by phone. (TUAM Vinetou,  Laguna or Intercity are amongst cheapest and reliable companies) .Very expensive are also taxis at the Ljubljana airport,as they charge almost double rate. This you can avoid with pre-booking one of the companies offering private or shared ride transfer from airport (BookTaxiSlovenija, Airtrail private transfers  or Markun shared ride)

For New Years Eve 31.12 -1.1. taxis in Ljubljana charge double price -  but officially you will get the bill for half of price! Always ask a taxi driver for receipt.

Always make sure you get in official taxi company otherwise a  price for ride that would normally cost you 3 -5 Eur would escalate up to 20 eur. Such "taxi" drivers are usually waiting in front of clubs during the weekend.