Priority 1: No aquifer. Aquifers are extremely difficult to dig through and can easily flood forts. If only PART of your embark location has an aquifer, you can dig around it. This would require two biomes in one embark. When there are two biomes in the embark area when you're looking on the world map, press the function keys to cycle through information about each one.
Beyond that, you'll want some trees. Woodland or heavily forested will give you basically infinite wood but can make building surface structures a bit annoying and if anything starts a fire your FPS will nosedive. Sparse trees are a good balance but if you run out (or just want to preserve the fruit trees) you might have to breach caverns early, which is dangerous. More trees is a safer option.
Rivers are very helpful, as they're easy sources of food via fishing, as well as fresh water. You can get by without, but if there aren't any ponds to drain into a cistern you'll be SOL and will have to breach caverns early, which is, again, dangerous. Injured dwarves need fresh water, they can't drink booze.
Ideally, you'll want deep metals (plural), shallow metals, and flux stone. Prioritize metals over flux. The more metals you get, the better chance you have of getting valuable metals for trade or useful metals for armor/weapons. Flux is necessary to make steel.
Soil, sand, and clay can all be used for farming, but clay can be used for ceramics and sand can be used for glass. If you can get them, go for it, but they're not a huge priority. They're nice to have.
With your surroundings, there's sort of an alignment chart here. Savageness determines whether giant animals and animal people appear, while evilness determines whether horrifying magical bullshit will kill all of your dwarves. Calm/Serene/Mirthful/Joyous Wilds surroundings are safest, Wilderness biomes are still pretty safe, Untamed Wilds are pretty dangerous, and Sinister/Haunted/Terrifying biomes can be extremely dangerous.
Warmer temperatures also mean surface water sources won't freeze over in the winter.
You don't need to tick all the boxes and look for a perfect embark here, basically prioritize no aquifer, trees, reasonably safe surroundings, and a river. The rest is good if you can find it.
Edit: Also use tab to see if anything nearby is at war with you. Goblins and towers mean you'll get sieges.