A few months ago, I got interested in air drops. Which basically are people or companies who create tokens or otherwise give away tokens to advertise their products-often the token itself. Some do an initial coin offering, and some don't. Originally I just collected tokens and would see what happens. I recently started to find out what they are trading for. For tokens that may ultimate be worthless, what they are trading for isn't exactly worthless as of this writing. Keeping in mind that they probably are ultimately worthless, I have no idea if it is legal to sell them in the USA. It isn't enough to pay for an attorney to find out one way or the other. I don't ever recommend buying any. But if they are free, you might as well get free tokens To learn how, You can scroll down past the horizontal bar if you want to skip all the reasons that I would avoid buying ERC-20s. But as you do try for them, know in advance that many will not deliver.
Ideally I tend to stick with those that have online wallets, and I try to avoid the ones that require you to download a wallet-and more and more frequently the downloads have viruses and it doesn't take a rocket scientist to know that's bad. So pretty much if it is waves or ethereum based, I may sign up for them. if i get them, I will look at what the company does or plans to do, but most have nothing viable to offer. My advice is always, do not buy ICOs and do not buy ERC-20s. As @Jefft shows us, the tokens are quite easy to make. https://steemit.com/cryptocurrency/@jefft/how-to-build-a-cryptocurrency-in-15-minutes . I was tempted to try making one myself as a demonstration, but it looks like it cost money to do and requires running a chrome extension. I'll pass for now.
Basically ERC-20s are just as bad, if not worse, than pink sheets. Although, When I am able to restart my company, I would definitely consider doing issuing an ERC-20 and launching an ICO and treat it as a security-obviously without the dividends and without the shareholder having votes in the company. But my advise remains, do not buy them. Maybe there are a few legitimate companies out there since they are easier to deal with than the SEC as of this writing, but you may want to physically visit the company (or hire an agent to physically visit the company for safety reasons) before investing money into them. Webpages, social media accounts, physical addresses, videos, photos, and most of the words spoken mean absolutely nothing as to the viability of what is behind the token. People can even clone the name and symbol of a token, but have a different contract address as the scam people out of their money. It is likely because of all the fraud that they will be regulated, and that when regulated, the demand for etherium will decline as will the prices. If you hold etherium, you definitely want to pay attention to how the governments will regulate tokens and ICOs.
Many times the sales pitch of ERC-20s are claims they are cheaper and faster than bitcoin cause they use etherium-but since you are using steem you know that steem is already free to transfer funds between steem accounts (there are fees in buying bitcoin with cash, then buying steem with bitcoin) and is usually pretty quick. but even if steem didn't exist why not just use ethereum in the first place instead of the added volatility of a token? To be fair, steem does have quite a few middle men too to go from cash to crypto, just not in transferring steem from one account to another. The latter part is why in the long term, it could be argued that Steem has more untapped potential than Ether or bitcoin. I am surprised there isn't yet a steem backed debit card.
Some Erc-20s claim they are building a community, well that would be nice if they were marketing something other than their token. Unless they find extremely niche markets, it sounds like ERC's do more to deter clients. Imagine a customer wanting to buy a product in dollars or through bitcoin, and a company says sorry you have to go through an additional 20 step process and buy our volatile crapcoins in order to do business with us. Lost business I think.
For those who would like to at least accumulate ERC-20s, the first thing you should do is create a new email address so you don't get spam. Protonmail, yahoo, gmail, etc.
Secondly, I would would go to https://etherdelta.com (most places recommend https://www.myetherwallet.com/ for airdrops, but myetherdelta has the exchange) and create a new etherium address. Print out the keys, and keep it safe. NEVER share your private key. Although to be honest, i did import my keys from myetherwallet into etherdelta. Bad me, Bad me. Well, I never (at this stage) put money into the account, but did later.
note: If for some reason you use an old eth address, it may not be token compatible.
-The site takes a long time to load. Where you see the black bar (I added the black bar to the image) at the top is a drop down list of supported tokens. On the upper right you'll see a drop down menu where you can create an account, or import one.
There are many sources to try to find free airdrops. I will say this in advanced, most do not deliver. Maybe out of 40-60, only about 7 have actually delivered tokens. Among the sites listing them are:
https://bitcointalk.org/index.php?topic=1438371.0
you can find airdrop listings on https://www.facebook.com/groups/freecrypto/ which I think is admin'd by 
you can also find some on, although it is a bit spammy now, https://airdropalert.com/
Many times you'll need to form a https://bitcointalk.org account and maintain a certain rank, and have a telegram account too.
Basically from there you fill out forms basically saying what your bitcointalk user id is, maybe the bitcointalk profile address, an email address, a telegram id, your name, and your public ethereum address.
-an example of a previous form
How will you know when the coins are deposited? It is unlikely that you will receive an alert. But you can visit https://ethplorer.io/ and paste in your public address and check. Every once in a rare while you'll find that one of the companies actually did an air drop.
Now assuming that you are actually sent some erc-20 tokens. You may not have enough to ever trade, so they become essentially dead tokens. Of the 7 that I received, about 3 are basically dead on arrival, and another isn't supported by the exchange. If you do find some that do have value, you'll soon realize that you can't trade them without physically holding ethereum to pay for the transaction.
How do you get ethereum? Well, surprisingly many exchanges do not accept cash because it is claimed they don't want to be involved in money laundering. There are a few who do accept cash, and i ended up finding and using coinbase. When I tried to make my first purchase, the bank blocked the transaction as fraud, and the location was from a place called "cheapside", which had me panicked. Started reading the reviews, and well it has tons of negative reviews, lost funds, international processing fees, and yet even more panic. I ultimately found a video by jerry banfield which said that was the one he uses, and called up the bank to see why it didn't go through. The bank didn't like their verification system (withdraw, deposit, withdraw, withdraw or something so quickly) and they told me to wait a few days. Today, I bought $10 worth of ether for "gas" aka transactions. I think that is the first time I purchased crypto itself, though I have bought cloud mining in the past. I transferred it over to my ethereum account to enable me to trade. I am not sure what all the distinction is between coinbase and gdax, but it seems jerry banfield likes gdax and was previously using coinbase. https://steemit.com/tutorial/@jerrybanfield/1-coinbase-tip-transfer-wallet-funds-to-gdax . Well at this point I could trade and cash in these tokens, and at least describe the process thus far.
But I won't allow myself too sell them at this point. While it is legal to hold these tokens, I have no idea if it is legal to sell the tokens [in the usa] bearing in mind that they may ultimately end up being worth nothing. Maybe one of my readers could answer this. I guess I will hold onto them until I find out a more definite answer. As far as the morality of selling them? it is the free market rate, and people who made it this far are pretty determined and ambitious and entering it through their own free will. They are most likely daytraders, speculators, or people throwing a few crumbs around to see what happens. There is a certain mathematics involved in risk, but I am not sure if they have a mathematical model that permits such losses or if they are just gambling.
Feel free to collect the free tokens.