Tips and Advice
Backup! You need a copy of your data in case of catastrophic failure. So many times I've been approached by distraught individuals who knew better, but never got around to it. We can clone to a fast Solid State Drive and then you'll be able to clone back to your Mac when necessary.
If your Mac is 8-10 or more years old, you'll benefit from getting a newer Mac. Any new Mac should have a Solid State Drive (no spinning parts). This is essential for the new operating systems above Mojave. Buy as much Storage and Ram as you can afford as they are not upgradeable later.
If you need an All-in-One printer I currently recommend Epson Workforce. Avoid HP, their software is garbage. For pure black and white needs get a laser printer (cheaper to run), Brother makes a good one for a reasonable price. While wireless is all the rage, you'll have less set up hassles and better reliability if you stick to models with a USB Cable.
Many of my new clients were living in Password Hell! You've seen it, passwords written on checkbook registers at all angles, some crossed out, most illegible. Take a look at PasswordWallet, they make a Mac ($20) and iOS ($4.99) version. https://www.selznick.com/index.htm
If you have programs starting at System launch, go to System Preferences>Users & Groups> Login Items and remove everything in the list except CCC User Agent. As well, when you log out, if you see the box checked that says "Reopen windows when logging back in", uncheck it! Having programs launch at startup can stop you cold, especially if you've accidentally installed some Adware or Malware.
Don't install Web Browser Extensions (in Google Chrome, Firefox, Safari) UNLESS you vet them first via a Google search to make sure they are safe. If you get prompted to install a search engine helper or anything else for that matter, back out! If you notice that your home page has changed or your search engine looks odd, you've probably been hijacked. Installing the AdBlock Extension can help you avoid getting tricked.