Internet sages are full of rules about stupid things you should never do. But like most recommendations delivered as inviolable laws, the cardinal Don’ts of life online mostly distract you from Do’s that would be more rewarding. Here are some don’ts I believe in breaking, and some dos you can undertake once you’ve let go of these time- and worry-wasters.

1. “Don’t forget to back up!”

The single most useful thing I learned from my dissertation research was from a hacker who said, “if you don’t have your data in two places, you don’t have your data.” Amen! But screw backups. Yes, you heard me right. Backups are like…oh, gosh, I’d name something I’m supposed to do everyday and don’t, but it would gross some of you out and make others of you ask, “am I really supposed to do that every day?”

Welcome to the 23rd-century internet (it’s arrived a few years ahead of schedule). If you’re using the web apps that you should be using to work in a smart, socially-enabled kinda way, the data you care about is already backed up. Between my Gmail archive (which contains all the attachments of anything I’ve ever thought useful enough to send someone), DropBox (which contains all the files useful enough to share with my team), MobileMe (all the contact and calendar data relevant enough to need on my iPhone), delicious (bookmarks), Flickr (photos) and Harvest (timesheets and invoices), Evernote (personal notes), I’d be hard-pressed to think of five files I care about but don’t have somewhere on the cloud.

Do spend the time and money you’d use for backups to get set up with cloud-based web services that will not only save (yeah, I mean back up) your data, but make it more useful in the process.

2. “Don’t buy the extended warranty!”

No, there’s no extended warranty on the Internet. (But wouldn’t it be great if there were? Just imagine: “Twitter’s having problems right now. But thanks to your extended warranty, our passenger pigeons will deliver that message for you!”)

But you can buy the extended warranty for all the hardware doo-dads you use to access the Internet: your computer, your router, your phone, that not-yet-FDA-approved neural implant. Any web site will tell you that you’re a sap for buying the warranty — don’t you know that’s how the big box electronics stores make all their money? — but sometimes being a sap is the path of least resistance. Yes, you could send your router to the manufacturer when it craps out after its first month, but it’s so much easier to drop back into Gigantic Electronics, hand them your dead router, and walk out with a new one.

Do spend your time researching your purchases before hand, in the hopes that your extended warranty will prove unnecessary.

3. “Don’t use the same password on multiple sites!”

OMG!! I must be crazy!! Well, how crazy do you get when you’re trying to remember which g**d*** username and password you used on the site you’re trying to log into?

The twin angels of Internet security and privacy will tell you to use a different password on every site, generated by a random algorithm, and whatever you do, don’t ever write your password down. There’s a name for those who can successfully implement that approach: supercomputers.

For those mortals who can barely remember our own phone numbers, let alone our passwords, something simpler is in order. I am awsamuel everywhere: this not only helps me remember my username when I visit a site, but it gives me a consistent identity online. (If you’d rather have anonymity in some circumstances, you may want a second username that you use for off-the-record sites.) Then I have four passwords: my I-so-don’t-care-about-this password (I’m almost prepared to include it in this post), my all-purpose password (for sites with no associated payment mechanisms, but where I post content and don’t want others to abuse my name), my high-security password (for servers, sites where I’ve given credit card info, and my own blogs), and my bank password. I change my all-purpose password about once a year.

Do write down hints about which passwords you’ve used on which sites. If I’m not sure whether I’ll remember whether I’ve used my all-purpose password or my high-security password, I create a contact record in my address book and note which password I’ve used for that site. I don’t write the password down, just a prompt that tells me which type of password I’ve used — enough to remind me, but not enough for anyone else to understand.

4. “Don’t store your main credit card number on e-commerce sites!”

This is a twofer: not only are you violating the law that Thou Shalt Have A Separate Low-limit Credit Card For Thy Online Purchases, but you are also violating the law that Thou Shalt Never Store Your Credit Card Number Online. 

Storing your number will actually save you money. If you’re like me, you’ll otherwise get around the inconvenience of having to get out your credit card for each online purchase by memorizing your credit card number. If you’ve done this, you may want to consider getting a new credit card (really). Knowing your credit card number by heart is a dangerous thing: it makes you prep to every ginzu knife commercial, every “let’s just order our dinner while we’re on the way home” — every opportunity to buy something now, today, this minute, before you even have to spend forty-five seconds getting your wallet and credit card out of your purse or jacket.

Using your real credit card saves you money too. If you use a credit card that earns points or rewards, you’ll get those points for your online purchases (a benefit you’re unlikely to get if you’re using a low-limit card as a secondary account for online purchases). And you’re unlikely to forget about that second credit card, racking up interest charges when you miss a payment.

This tip doesn’t apply to every site: if this is your first purchase at Andy’s Widgets ‘n Things, you might want to use PayPal, or another disposable payment mechanism (like a pre-paid Visa gift card) But there are some sites you use regularly, and advisedly — in my case, Amazon, TicketMaster and iTunes. (OK, maybe not advisedly…but regularly.). It’s a pain to dig out my credit info each time….and I use them frequently enough that digging out the credit card is recipe for credit card memorization. So for sites like these — sites with a huge number of customers and a reputation that assures you that your credit card statement is unlikely to include a surprise charge of $892 for porn and sex toys — go ahead and store your number. It’ll make your life easier, you’ll earn points on purchases, and you’re less likely to experience credit card theft on a mainstream online site than in some restaurant where a waiter can write down your number for later use.

Do worry about that waiter with the $10,000 Rolex.

5. “Don’t pay for stuff you can get for free!”

The web is full of fantastic free content, available both legally and illegally. Bittorrent will get you the music and video you want, a decent google search will find you great tech support, and almost any kind of software you need is available in an open source, install-your-own version. And since you have a limitless amount of time and a finite amount of money, it’s a great idea to get everything you need for free.

What’s that you say? Your time is finite too? Possibly even more limited than your money? Great news: let me introduce you to a little something we call the credit card. Yes, those bastards at [insert name of video site here] are selling you what you could get for free, those idiots at [insert name of tech help site here] are selling you info you could find yourself, and those schmucks at [insert name of on-demand software company here] are charging you money for software that isn’t even half as good as what you could put together yourself. But one day you will be dead, and meanwhile there are only so many hours you want to spend searching for that video file or how-to tip, or installing and configuring your own software.

Spend the money: iTunes or Amazon will get you that video or song right now, MacFixit will give you that tech answer in two minutes, and software services like Harvest, ManyMoon and Batchbook (love you guys!)

I know you know how to do it yourself. So what?

Do spend your time and tech smarts in more useful ways to have more impact — and make more cash to cover those online content bills.

* * *

I realize I’m taking my online life in my hands with these recommendations; that there are those who will see this as a giant “hack me” sign. But I also see too many people who are daunted by all the rules — all the endless don’ts — that make life online harder than it needs to be. Best practices need to presented as just that: best practices, recommendations, words from the wise.

When we load Internet users with iron laws — with don’ts — they all-too-often hear just one: don’t trust the Internet.

And I’m more interested in conveying a do: do embrace the potential of life online.

What online don’ts have you disregarded? What online do’s have you embraced? Let us know in comments below, or via Twitter.