Laptops typically come with loads of unnecessary bloatware and startup utilities installed, which all adds up to a fair amount of RAM being used before you even start doing anything, and with only 4GB of the stuff, it's essential you get that sorted.
Check for any software you will never use & uninstall it, especially trial versions of things like Microsoft Office or MacAfee Antivirus.
Check your startup items and disable any non-essential ones, be as aggressive as possible with this, you can always re-enable them if necessary later on.
CCleaner will help you to get your startup items under control:
https://filehippo.com/download_ccleaner/
One word of caution: CCleaner has a "Registry Cleaner" module, don't use it, it's potentially...