To access the Tor network and hidden services some software is required. Luckily, there is a complete operating system (such as Windows or MacOS) called Tails that is build especially for this and it adds other useful features on top. Learn here more about Tails and how to use it.
Tails is an operating system which is made for privacy and anonymity by following principles:
One good thing about Tails is that you can simply install it on a USB flash drive. After using Tails it forgets nearly everything you have done over it, unless you want to save some information.
Although it is possible to access the Darknet without Tails and just with e.g. the Tor browser bundle, we do heavily recommend using Tails due to the mentioned benefits above. Besides this, the Tor browser bundle can not be considered as secure enough for buying or selling anything on the Darknet.
As mentioned before Tails can simply be installed on a USB flash drive. We are happy that the Tails team offers a really good installation documentation at tails.boum.org
What you will need for this are two USB flash drives (at least 8GB), download Tails (1.2 GB) and one hour to install it. If you have a friend already having a Tails installation it is even easier (explained in the installation documentation).
The first thing which cannot be emphasized enough is that you should not stop thinking when using Tails (or the Tor network in general). Note that you can still reveal personal information if you for example use your personal email address in Tails. Also, do not store any information on Tails that is directly related to you. The chance is very little, but there might be some circumstance that someone gains access to your not locked Tails.
The second advice is, please update your Tails always to the latest version. You are informed about a new Tails update with a popup when starting Tails. Please take the few minutes to update it, as new updates may fix security vulnerabilities.
Take the time and inform yourself about your general internet access. For topics like like WiFi or VPNs have a look here: Internet Access
Backup your data from time to time. It can be a pain if you loose your USB flash drive with Tails and do not have a backup with e.g. your private PGP Key or your Bitcoin or Monero wallets. The easiest way is to create a complete copy of your Tails USB flash drive with your primary operating system (like Windows). You can also only backup your persistent data, as described in the official guide at tails.boum.org.
As the official Tails documentation is pretty good we will not explain more at this point. Just have a look and spend some time here: tails.boum.org