I actually enjoy the design part - drawing schematics, mulling over different approaches, minimising the component count. But if you dont have the training, there is a lot to learn and part of the way you learn is by getting stuck in and trying things out.
The other thing to consider is what is the cost of failure. There are not many components that you are likely to use that cost more than a few dollars. Even if you think you have killed your Arduino board, its quite likely you have just killed an output transistor on the AT Mega ($5). Erm yes I have done that.
If its just a project for yourself and its never going to be built by anyone else, then there is not much harm in overdriving components and exceeding their tolerances. If the project fails after a while, then that just means you get a chance to play with it again and improve it.
You'll also learn something too. Even if its just 'do a bit more design to avoid frustration'
Si