Here are a number of resources I use to both manage my business and to some extent my life. They are all recommended although I suggest you look at them to see if you need them and if they are a good solution for you!
Many have free versions available and some are entirely free.
Google Flights
I fly a lot. I probably spend nearly as much time setting up and hacking flights.
I'm often not only looking for good and convenient flights, but also trying to squeeze in a few day side trip generally at no cost to somewhere interesting. Lately I've managed Amsterdam, Athens, Copenhagen, The Canary Islands, and Krakow, just looking at overseas.

Google flights is a favorite, and free, tool.
Hint: Sometimes booking openjaw trips and paying for a connecting flight separately is much cheaper when trying to fit in another stop!
Thunderbird (email client)To read and write email, I use the free Thunderbird client and have for a very long time.
Email clients are very much personal preference and this in mine (way way back, I used elm and mailx!)

For sending email to lists of people, like probably you sometimes, an email client is NOT what you want.

You want something absolutely optimized for the purpose. Email clients are NOT designed to send email to hundreds or thousands of people! I use AWeber for that, listed below.
Email: AWeber (Free Version Available)
Much of my business is run by email. I use AWeber for my email list and email management.
It manages my email broadcasts, lists, fills my classes, webinars, and other events.

I have used and recommended AWeber for many years! I've found it ideal for small to medium businesses. If I ever scale to 7 and 8 figures I may use something else with more features although some of the more complex solutions seem to require a support team or consultants to set them up and I do not want or need that complexity. They do have a free trial version for up to 500 emails with no time restrictions - ideal to get started and maybe even your first year or longer, as well as free migration services.

Why AWeber? Superb deliverability, pricing, and ease of getting started.
Webinar Software: WebinarNinja (Free Trial Available)
I have been using WebinarNinja since it's been in beta and very happy.

Most of my webinars and classes are done using WebinarNinja and I heartily endorse it!
It's not perfect, nothing is, but after using at least a dozen different platforms, I have settled on WebinarNinja, and it keeps improving. They have great support!
Online Payments: ThriveCart
I have been using ThriveCart for online payments for a longtime and expect to continue to use it forever.
I actually started using it when it was in beta!

My paid courses, paid webinars (most are free), online conferences and more use ThriveCart for payments via credit cards, PayPal, and more.

It's been easy to use and reliable - much better than what I used before!
Zoom (free version available)
Yes, I use Zoom - a lot. They also have a free version available I used for years.
I now pay for an inexpensive version which gives me far more flexibility.

I use it for conversations, interviews, and occasionally interactive broadcasts/webinars as well.
Vimeo (free trial available)
I have used Vimeo for video hosting for a long time.
Vimeo is inexpensive, it gets the job done, and I can't imagine ever going over my bandwidth limit.
Photoshop Elements
I use Photoshop Elements for basic image editing.
Yes, it can do more and there are other options too, but I find it pretty simple and easy to use.
I've used it for years.
I do ALL my video editing in Camtasia.
If you see a video from me that looks like a 2 camera shoot, it's probably just some simple tricks in Camtasia.
Supposedly the Mac version doesn't have all the features of the Windows version.

I use Camtasia a lot!
Disclaimer: I only recommend things I like, and most I either use currently or have in the past. Some of the links may be "affiliate links," meaning that if you click through and purchase a product or a service, I may receive a commission. You pay the same price whether I receive a commission or not.