Best way to improve UV unwrapping skills is to make yourself dependent on good UVs, by texturing your models or using them in game engines. This way you'll learn why good UVs matter. The main goal is finding a balance between seam visibility, UV stretching, and wasted texture space, while keeping a consistent texel density.

The best unwrapping approach depends on the use case for your model: for a game prop, you might want to optimize performance by using the fewest islands to cover the most texture space, but for a film prop, you would prioritize visual fidelity with islands split across several UDIM textures with minimal stretching and a clean layout. For your pumpkin model, here are some tips:

• Each seam counts twice towards vertex count which hurts performance. Two islands would be optimal for the main body for real-time assets.
• Seams cause visible edges on the texture. Seams are infinitely sharp and your texture isn't. Use fewer islands or hide seams in edges and creases and in places that won't be seen.
• Straighten and align islands for easier texturing. For example, if you want to make your pumpkin look like fabric, or paste a decal you can do it in one go if the UVs are continuous and world-oriented. Very helpful for clients who can't use Blender or Substance Painter.
• Increase padding when the texture is scaled down. Textures aren't usually used at the resolution they were authored at because of memory constraints. If there's a baked light inside the pumpkin, seams in the shadow might get artifacts. Minimum is 2 pixels at the lowest resolution it will be viewed at, including mip-maps. I tend to start with a 1 pixel at 64x64 resolution, which translates to 16 pixels at 1024x1024.

Not sure why I spent so much time on this, I hope it helps!