Honestly, any paint program you're comfortable with will work, it just all depends on what you're comfortable with using and doing. I know people who swear by graphics gale for all their spriting needs while others just stick with gimp or photoshop. MS paint is already pixel-based by default, but it lacks a lot of useful advanced features and doesn't have transparency. Some people use a combination of multiple programs too, and that is perfectly fine.
If you want to look at other programs though,
graphics gale,
grafX2,
Tile Studio,
Moai,
Asepirte and
Jpixel are all free programs I've heard people using over the years dedicated to sprite work.
Piskel is a free online program if you don't want to download anything. I still recommend you stick with what you know though unless you're really looking for something different. And for the sake of future readers, or maybe you simply do not like any of these choices the website
alternativeto can be a good starting point for other programs.
A couple of important things though to keep in mind, I'd suggest turning on the grids or grid lines so it's easier to keep things within proper sizes and eyeball the work you're doing better. I would also get familiar with the various effects and filters. You know, the ones you'd use to adjust the colors or brightness, the color balance, the gamma settings, it can save a ton of work if things don't look quite right.
Here's how to set up Gimp for pixel work, and
here's a topic on using paint.net to set it up for pixel work too!
If you're in need of tutorials, there's a few places out there to look for.
2Dwillneverdie,
OpenGameArt and
Pixeljoint are good starts, but there's plenty of other places with them too.
Learning to Dither can be helpful if not a must depending on the style you want. (a shortcut for dithering is looking for screentones)
Some tools you might be interested are things like
color ramp/gradient for finding colors you might want to use (or at least give you a start if you need it) If you want something more advanced for your color palettes, you can always look toward
others preferred colors. If you know how to put
in custom brushes in paint.net, you can probably make pixel based brushes to help make things easier. Someone also made an
animation effect for paint.net specifically for spriting. Gimp also lets you make
custom brushes but if you still need help getting a pixel brush for it
there's this.
It really all comes down to what you like and what works for you and what feels comfortable though. Sorry you couldn't find help before, but I hope this helps o 3 o/
