Setting up a bitcoin miner can be as simple as downloading a mining client program, or as complicated as building a custom rig.
Bitcoin mining used to be cheaper and easier to do than it is today, but it can still be relatively simple to execute. In the past, a computer with a CPU could crunch through enough hashes to solve a few blocks and turn a profit. Now, a good GPU, that is, a Graphics Processing Unit card connected to the motherboard of a computer, or a series of GPUs, is par for the course because they can perform many times as many hashes per second than a CPU can alone. This is the case even if the CPU has several cores, and it just has to do with the way that GPUs handle their work.
There are also hardware mining rigs that can be purchased as stand-alone units, some of which only need to be connected to a standard PC power supply (PSU) powerful enough to run the rig. These units only serve the function of mining bitcoins, and usually come pre-loaded with all of the required software for mining and communicating with the blockchain and even a mining pool. Some do require a little programming or customization with languages such as Raspberry-Pi, so if this is not your cup of tea be sure to avoid rigs that require any coding experience.
Joining a mining pool is an increasingly popular option for getting involved with bitcoin mining, and many pools are open to join at no outright cost to the miner. Many stand-alone mining rigs make use of ASIC technology, which is designed specifically for mining bitcoin, and most ASIC rigs are manufactured in China. The code in a mining client software will often also tell the user how much power has been used, the average fan speed and temperature of the rig due to mining, and other statistics that can help determine the profitability of the operation.
The primary cost that miners have to consider is the cost of electricity that powers the rig, and potentially the cost of cooling the room beyond the capacity of the fans and onboard cooling devices. Popular mining software names over the years have included CGMiner, BFGminer, Bitminer, BTCminer, and others.