It'll probably come down to trial and error. Just remember, there are two basic strains of cannabis... indica and sativa. Indicas (aka in-da-couch) will provide a more sedate feeling and is good for relaxing or sleeping. It's notorious for what we call 'couch lock' and shouldn't be used if you have things you'll need to get done later in the day. Sativas offer a more energetic or euphoric feeling and are good for lifting your mood and may help with depression in some people.

Of course there are also varieties that offer less THC (the psychoactive compound) and more CBD (the more socially accepted medical compounds) than others. If you are in an area that has cannabis readily available, I'd suggest dropping by a shop and speaking to a good budtender. You can usually purchase pre-rolled cigs that would allow you to try various varieties to see what works for you.

Good luck and have fun.