I've been half in, and half out of SL for a long while. With COVID, I needed to "get out" so I came back. I decided to go mesh because, well, what else am I going to fuss about.
There are resources, and it involves a bit of figuring. The good news is, on a practical level any of the mesh bodies out there are fine. You can get a desired look with any of them. TBH, I can't tell visually the difference between any of them. On females, Hourglass is more curvy than Maitreya, but I've seen very slim HG shapes and very curvy Lara shapes.
As Yogi Berra would say, 50% of your look is 70% your skin. I can tweak my face sliders a but, but the shading and coloring of the skin makes a bigger difference. Thankfully, BOM makes this easier to get into. As long as the body is BOM-compatible (and most are) you don't need to worry about appliers. So, I'd say at the least finding out the skin used, and if there is a BOM skin for it (it will have an icon that looks like a stick figure going, "I dunno." Most of my shape edits are rmore roughing out a look than fine-tuning.
Skell's blog has a lot of great how-toos, and was very helpful for me getting going. Also, Urban-Maan has style cards for looks. You're not going to look 100% like the photo, but hopefully at the least the creator can go "here, use this shape." Maybe lean a little on the "I'm new coming back, please please help me."