If you don't have a multiengine rating, get one. Once you have that, do whatever it takes to get rides in any twin you can.

It's called network, network, network. That's the secret.

Find the airports around you that have twins and find the owners. Get to know them. Offer to wash their plane, help out with the radios on a trip with them, watch out for traffic, anything to get rides.

The more you are at the airport, the more people you meet, and the more rides you get. Eventually you'll meet someone who owns an airplane, and doesn't even fly it much! Offer to fly with them or for them.

It takes persistence and dedication, but it works. That's how I did it. I flew several nice Barons and C-310s over the years to build time.

Good luck.