I think the biggest impact to start with would be a decent grinder so you can start buying whole-bean coffee and grinding it right before you use it… pre-ground coffee gets staler, faster, so by grinding it at home, you’re going to get a fresher cup.

An electric burr grinder is going to be more expensive than a crappy $20 “whirling blade” grinder, but your grounds are going to be more consistent is size, which is important for getting consistent results while you experiment with other factors like brew time, water temperature, etc.

If you can’t swing an electric burr grinder, there are some fairly affordable manual (hand crank) burr grinders that produce good results.

From there, French press or Aeropress are pretty low-barrier-to-entry ways to get started.

For travel, I take a hand grinder, mug and an Aeropress, and buy beans from a local coffee shop to grind. All you need is a way to heat water, and you can do good coffee anywhere!

Hope this helps, happy coffee-making!!