Before starting, you already need to have a wallet configured and working. The pool needs to know your wallet address to be able to send payments there. See the Accepting Monero guide for more information.
Before mining, you should decide if it is worth it or not for you. You have to decide this for yourself, based on your power costs and the hardware that you have available. There are many sites, such as CryptoCompare that allow you to enter your miner's speed and power draw, and it will show you the profit (or loss) per week/month.
The first step is to download mining software onto your computer.
The XMRig developer provides pre-built binaries for Windows users. They are available on the GitHub release page.
Scroll down until you see
this file and extract the archive somewhere memorable, like your desktop.
The XMRig developer provides pre-built binaries for Ubuntu Bionic (18.04) and Focal (20.04). They may work on other Ubuntu versions, and on other distributions, but this is not guaranteed.
These binaries are available on the GitHub release page.
Scroll down to 'Assets' until you see the correct version for your system. Download this file, extract the archive somewhere memorable, like your desktop.
Binaries are available for multiple distributions and operative systems, but you can also build the miner by yourself. Take a loot at XMrig's docs
There are lots of pools to choose from. You can find a list at miningpoolstats.stream/monero.
Choosing a larger pool means that you will see more frequent (but smaller) payouts, but choosing a smaller pools helps keep the network decentralised. Miners will not lose any revenue by mining on a smaller pool.
See the official docs, for instructions and suggestions.
Windows users can double click on xmrig.exe. Users of other operating
cd into the directory that contains XMRig and then
./xmrig and press return.
If you see green messages saying that shares have been accepted, congratulations, everything is working!
Some anti-viruses flag XMRig as malware because it is often deployed to infected computers to mine without the owner's consent. As it is your computer and you are configuring the miner to mine for you, it is safe to add XMRig to your anti-virus whitelist.
On some CPUs, XMRig tries to increase performance by disabling certain
features like your CPU's instruction prefetcher. These operations
require root/administrator, so try right clicking xmrig.exe and
running it as administrator, or running
sudo ./xmrig on other
Find the line in config.json that says
algo: null and change it to
algo: "rx/0". By default, XMRig expects the pool to tell it which
hashing algorithm to use.
Taken from the MSDN:
You may also need to launch the miner as administrator.
Firstly stop the miner (if it's running), run the following commands to enable large pages and then start the miner as root:
sudo sysctl -w vm.nr_hugepages=1168 sudo ./xmrig
You may have to increase 1168 depending on how many NUMA nodes your CPU(s) have.
Huge pages are not supported on macOS.
Most pools are PPLNS pools, which means that you only get paid when a miner on the pool finds a block. If the pool you are mining on is small, this can take a few days to weeks.
Additionally, any blocks found must mature before they can be paid out. This takes 60 blocks (approx. 2 hours).