Use a pipe. Spliffs constantly smoke, so some gets in the window. Pipes though, you can put out after you get a hit with the end of your lighter. Spliffs get your fingers very smelly, pipes though, don't.

I used to smoke joints out my window too and got busted everytime. I used a pipe for the longest time, and I never got busted once.

So I'd use a pipe if you must toke in your room. Other than that, the weather is starting to get nicer, so I'd just go outside.