GoKawiilBacking up is always the important first step, even before transferring files to a new laptop. On a Windows PC, you can use Windows Backup by searching for it in the Start menu. You'll see a list of what can be backed up to OneDrive and when you last did. While convenient, its major roadblock is that free Microsoft accounts only comes with 5GB of cloud storage. You can subscribe for more if you like; another option is making a local backup to a portable HDD or SSD. While you can copy files to the drive manually, EaseUS Todo Backup's free version is a good choice for automating this. Since Windows Backup covers settings like account details and personalization features, a combination backup is smart.
For a MacBook, use Apple's Time Machine. The built-in macOS backup tool can back up everything onto a USB drive so you can recover it on another computer. Visit System Settings > General > Time Machine > Add Backup Disk, then select the storage device you have connected (ideally with at least twice the storage of your MacBook) and follow the instructions. You can also use iCloud to back up some kinds of data under System Settings > [Your Name] > iCloud > Saved to iCloud. Apple offers only 5GB of free storage, but you can subscribe for more.
Third-party backup software and cloud services can also work. As a supplement to the full backup, double-check important apps, like enabling sync in your browser so you don't lose your bookmarks. Also check the ports on your laptop to make sure you don't leave any accessories behind, like small USB dongles or SD cards.
Before you move on, sign out of all accounts and de-authorize software licenses for tools like the Adobe suite. Some licenses can only be used on a certain number of computers, so you don't want to have a phantom machine wasting one of your spots. If you're not sure whether your license can be moved to a new computer by signing into your account, copy the license or product key so you can contact the provider.