One of the most exciting parts when working with resin is choosing and buying molds. I have spent so many hours and hours trawling through shops online looking for certain shapes and sizes when I have an idea in mind.
When buying molds for resin I would say its best to buy silicone molds. They're so flexible and very easy to bend if you need to pop your finished resin piece out. Some molds will give your pieces a nice finish, and you should be able to tell beforehand if your mold has a shine on the inside or not. From experience this means your piece will have a nice gloss finish, and minimal sanding and polishing will need to be done.
Molds do wear down over time with the more and more use, and that high shine will start to dim. There are different products you can use alongside your molds to keep them working great.
I've been successful without having the need to use any extra de-molding agents, but if you want to keep your molds looking their best this is a way to do that. Here is what I have used a few times... Pebeo Gedeo Vaseline Liquid
You can also Google search for resin de-molding agents, and also look on eBay! They have everything on there and its usually my go-to place!
Don't go out and buy loads and loads of molds to begin with. Start small, and start with something like a pendant. You can search for these through Google, as well as online shops like Amazon, eBay and Etsy.
Here are a few molds that I have. There are 3 pendant molds and 1 ring. To save you having to drill a hole into a pendant these molds have the little piece of mold at the top so your pendant will come out with a hole. These molds are made of silicone, and bend really easily. They can also wear down after a lot of use, which is a bit of a pain, but you can buy them quite cheaply online as well as use de-molding agents to help keep them in working order.
This is what you can make with one of the molds pictured above
I made this using the square pendant mold, and a beautiful pressed daisy. You will need to make sure your flowers are pressed for molds like these, because they're not very deep.
Well I hope I've given you some good information. Tutorials will be coming soon I promise! And if you have any questions or feel I've missed something off (I probably have!) Then let me know and I'll try to cover it.
Good luck and keep practising