How it is working?

Uniswap is a decentralised exchange (DEX) which runs on Ethereum and uses liquidity pools. People have to add liquidity (deposit coins) to Uniswap pool (half of ETH and half of some token) and he will get Uniswap pool tokens (UNI-V1) which can be sent as normal tokens and you can redeem money from that pool. The person who will want to exchange his crypto will just make smart-contract and exchange his crypto, but with 0.3% fee for liquidity providers - you.

What to do?

You need only Metamask (plug-in) for web browsers or if you have mobile (iOS or Android) you should use Coinbase wallet (its not that exchange, but normal crypto wallet), internet connection and some crypto to deposit it there.

1. Look at uniswap.info

There you can find stats on how are pools working, what was traded amount and also how much money is in that pool.

Now you have to find the most profitable ones. When I am looking for them I choose to line it up by volume from higher to lowest one. Then just compare volume and liquidity and try to find the best price ratio (bigger volume and lower liquidity is better) and then try to count what profit you would have. Volume / Liquidity * 0.3% * Your invested amount = Your daily profit.

I found SAI. It has a good ratio between liquidity and volume and also it is stablecoin so you are "safe" and you don't have to worry if it will fall more than 50%, cause some whale has sold it. ZRX token has the same or even better ratio, but it had a huge price rise (37%) and there must come some correction so you can lose about 20%.

Before buying SAI don't forget to look at the detail page - click on SAI name. There you can see recent transactions at this pair, liquidity and volume and by smaller numbers, it is written daily change of volume and liquidity. Look at volume change and check if it is not higher than 50% or more or if liquidity % decreased by many percents. It may go back to values in which it was before and you will not have a stable income.

For every 10 USD in that crypto, you will earn daily 0.046 USD, but the real amount may vary. If it is everything OK you can add money to the pool.

2. Adding liquidity to the pool at uniswap.exchange

As I wrote at the beginning of the article you are adding to the pool 1/2 of ETH and 1/2 of the token (SAI now). So now you will have to change 1/2 of your Ethers to SAI, but keep 1 USD in ETH in reserve, cause smart-contracts are not cheap. When you will exchange your crypto it will run smoothly and you just pay a transaction fee. 

After exchanging your crypto you will have to get to the pool tab. There you will have to write how much you want to add to the pool. If you exchanged SAI and there are many decimals you can easily click on "balance" button which will be right above the name of the token. You will have to unlock your SAI for few cents on transaction fees and right then you will be able to make smart-contract to add liquidity. If your transaction will Run of gas just do everything again, but when you will have to make confirmation from Metamask click on button EDIT and up there will be Advanced tab. Find the gas limit and add a few thousands of units - it will cost more, but it will work and your transaction will be approved. 

And you are done!

How to check my profits?

You can use Zerion.io. That is like some centre where you can lend money, borrow some or exchange them. Also, you can add liquidity to trading pools on DEXes. So just add your wallet thought Web3 interface and you can see how is your money performing. If you want to see only performing your money at Uniswap click on Invest at the page and you can see how much money you earned on fees and how much you earned totally - it is good when you also want to HODL that token and you will be able to see yours profit.