One of the easiest and time saving things you can do to voice your opposition to Trump is to call your Senators and just simply say "Don't support or do support" whatever the issue is you're interested in.
Union of Concerned Citizens sent me this email to ask Colorado Senators' Gardner and Bennett to say no to Scott Pruitt's for EPA administrator.
Sen Gardner ph 303-391-5777
Sen Bennett ph 303-455-7600
You can literally call and say to the person answering the phone or on the message that you want them to vote against Scott Pruitt for EPA Administrator. Senator Bennett's office answered the phone when I called and Cory Gardner only and voice mail.
Please do your part and call!