The vast majority of trading content is going to be about entries and exits. There are a few rather dull rules though which can quietly cost you money or get your account restricted if you don't know them. Two of the biggest are to do with settlement in a cash account and how your trading profits are taxed. Neither of these is particularly exciting but both are absolutely worth knowing about before you start trading in any significant volume.
Start with settlement. When you buy or sell a stock the trade doesn't settle immediately. The shares and the cash actually change hands a short time later. In the US the standard settlement cycle for stocks and ETFs is now T+1 (one business day after the trade) which replaced the old two day cycle in 2024. So if you sell a stock on a Monday the cash is settled on Tuesday.
This is most important in a cash account where you can only trade with funds that have actually settled. If you sell a stock and immediately use the proceeds to buy another security you're effectively using unsettled funds. That's permitted in certain circumstances but if you sell the new security before the original cash has settled you're in breach of good faith. The broker will typically issue a warning after the first instance and may place a restriction on your account (often for 90 days) if you go on to breach it several times. The rules will vary from broker to broker so you need to check your own.
A margin account gets round some of the issues in that the broker lends you the buying power whilst the funds are settling. Margin accounts do however have their own rules (the pattern day trader rule being the most well known of these) which in the past has required a minimum equity balance for those who are engaged in a large number of day trades over a short period. Regulators have been talking about changing that rule so it's worth checking what the current requirement is before you go on any number you come across online. For the swing trader who is holding their positions for days or weeks this is generally not an issue at all, but it's good to be aware of it.
Taxes are a function of how long you've held the position. In the US, profits from stocks held for one year or less are generally taxed as short term capital gains (at the same rate as your ordinary income). Profits from stocks held for longer than one year are generally taxed as long term capital gains (which are generally at a lower rate). Swing trading by definition is a trade that lasts days or weeks so almost all of your gains will be short term. That means taxes will take a chunk out of your profits and you need to remember that a $ 1,000 gain is not actually $ 1,000 of money that you can spend.
Losses count as well. A loss on a stock sale (i.e. one where you sell for less than you paid) can generally be offset against gains on other disposals and in many cases a limited amount of the loss can be used to offset other income with the balance being carried forward to future years. That's why a losing trade is not a total waste. It can reduce your tax bill. You should never however hold a position or take a loss simply for tax purposes.
The wash sale rule is the one that catches the active trader out. If you sell a stock at a loss and then buy the same stock (or a stock which is substantially identical) within 30 days before or after that sale, the IRS will generally disallow that loss. The loss is not lost forever, it just gets added to the cost basis of the new shares so you can't take it in the year of the sale. For the swing trader who is going to be trading the same tickers over and over again, wash sales can accumulate and make year end tax reporting a bit of a nightmare. It's therefore sensible to keep your books very clean.
On the subject of records, your broker will send you a form each year (the 1099-B) which will report your sales and most brokers will adjust for wash sales in the same account. If however you trade the same stock in two different accounts the broker may not pick up on that and you're still responsible. A simple spreadsheet or indeed a journal which logs every trade with the date, price and result makes tax time a whole lot easier and will go a long way to helping you establish your actual after tax performance.
A few practical habits will help. Set aside a chunk of each profitable trade for tax purposes so you're not caught out later on. Be mindful of how close a position is to the one year mark before you decide to sell as waiting could alter the tax treatment (though you should never hold a trade past your original plan just for that reason). And of course you need to bear in mind that the tax rules are different in different accounts. Retirement accounts such as IRAs have different rules and some of them are in fact completely tax free on trading gains until you take them out.
One more point for the younger traders. With custodial and youth accounts there can be their own rules about who owns the account, who reports the income and how the income is taxed. If you're under 18 it's definitely worth having a chat with a parent or guardian and a tax professional before you go making any assumptions.
This is general education, not personal financial or tax advice. The rules are always changing and your circumstances will be unique to you so be sure to check the current IRS guidance and your broker’s policies and consider seeking the advice of a qualified tax professional prior to making any decisions.