Definitely easy to get overwhelmed with materials. I assume someone pointed you in the direction of Silicone for your molds? Thats first and most important. You can use a lot of other types of rubber for molds, some at even half the price or less than silicone, but believe me silicone is the best and what you saved in money you end up putting back in time and sweat, especially when you’re just starting out, and Silicone is a lot more forgiving.
To start casting some resins are better for certain things than others. All have their pros and cons; like polyester resin is great if you’re doing fiber glassing, want to make clear(ish) parts or just need to save money, but it can be a bit brittle, it reeks to hell and back, so you need ventilation/respirator, and the chemistry involved can be a bit weird as far as calculating how many drops of catalyst to add to the mix, but mess that up and you end up with a sticky toxic mess that will never cure …
Epoxy resins generally will give you better clarity, and doesn’t ‘feel’ as toxic as polyester (respirator is still a good idea) but generally are thicker (like honey or molasses) so you’ll have trouble with air bubbles trying to cast with it, I tend only to use those for water effects in terrain or like clearcoating tabletop/furniture…
The best resin for miniature casting IMO is Urethane resin. Its (usually)a two part 1:1 mix, pretty forgiving if measurements aren’t dead-on, as in you won’t have that sticky mess if its slightly measured wrong. When hardened its pretty similar to plastic, maybe a tad more brittle. My recommendation would be for Instacast from Smooth-on if you can find a local supplier. I live close to this shop, and the owner is a cool guy so I usually get it here; DOUGLAS and Sturgess
or something like this; /https://www.smooth-on.com/products/smooth-cast-305/
if you click the smooth-cast section here it breaks down the pot-life vs cure times for their casting resins, you definitely want a few min to get it mixed and poured, (and pressurized if you’re going that route too) but you prolly don’t want to wait overnight for every cast, so 20min-to an hour would be reasonable https://www.smooth-on.com/category/urethane-resin/
The other domestic supplier I’ve had good luck with is Silpak – pretty similar products to Smooth-on and DnS http://www.silpak.com/#
For your first test you should do something simple to get a feel for the process, like bases or a flat.
This icon came from this mold, it was easier to pour a partial cast than try and cut from the panel
For a 3D object like a mini, you’re going to need a box mold, but that gets into planning vents and cutting the mold open, which is another set of challenges
It can be tricky, but once you get the idea it’s not too hard, and I’ll discuss that later