The advice is all great on this post so far. So I'll just share my personal experience. My boyfriend is slightly shy. I embarrass easily. Trying to bring up the idea of sex toys was terrifying.
I had a lot of lubes/heighteners so I started working those into our regular sex. Warming lubes, things to enhance my clitoral stimulation. He loved the idea that sex was better for me, so I suggested we look at this site together. I did reaffirm many times that I just wanted to spice things up, but completely loved our sex life. We chose a cock ring. Tried that, loved it. He's now quite addicted to sex toys and this site.
The most important thing for us was keeping communication open. We talk about pretty much every toy purchase we make. We both know each others limits and we don't cross them until the other gives it the okay. A lot of the advice on here is really good. Best of luck!