General attempts:
* Attempting
* Endeavoring
* Striving
* Efforting
* Assaying
* Seeking
* Aiming
* Aspiring
More specific attempts:
* Experimenting (if testing something out)
* Practicing (if working to improve a skill)
* Testing (if examining something)
* Probing (if investigating something)
* Tackling (if facing a challenge)
* Battling (if facing a difficult situation)
* Struggling (if having difficulty)
Informal words:
* Giving it a go
* Having a crack at it
* Taking a shot
* Giving it a whirl
More formal words:
* Pursuing
* Undertaking
* Engaging in
The best word to use will depend on the specific context of your sentence.
For example, if you're talking about someone trying to solve a puzzle, you might say they are "attempting" or "struggling" to find the solution. But if you're talking about someone trying to learn a new language, you might say they are "practicing" or "endeavoring" to improve their skills.