Onshape (onshape.com) is generally a good starting point - its cloud based, so the usual PC performance requirement issues don't apply. Free accounts require you to have publicly viewable documents, so if you're working on something for profit, you might want to splurge for the paid version after you get up to speed.

I’m a big fan of Fusion360. It’s easy enough to learn, full of online resources, and is free for tue first year. It’s also powerful enough to do machining (CAM), which is incredibly useful for manufacturing and scaling down the line.