Clonidine lowers blood pressure, so try to be aware in a general way of your BP from day to day. If you become Hypotensive from the Clonidine, you run the risk of passing out and falling among other stuff. Now, the Benzodiazepines are the most significant issue. Clonazepam (Klonopin), like other Benzos, can be dangerous when used alongside Opioids like Methadone. Their combined use can lead to respiratory depression and potentially death. You should try to be aware of your respiration and try to make sure you're not becoming too sedated.
This doesn't mean that those who use Opioids should absolutely never use Benzodiazepines, in fact, there are a lot of legitimate reasons one might have for needing to take them, it just means that greater caution must be taken.
How long have you been on your Methadone dose? How much Clonazepam are you scripted?