first, invest in double paned PVC windows. dami supplier sa mga home depot. high end ones like Kenneth and Mock boast of almost complete soundproofing. sila na rin mag install.
next, build an insulated drywall on your existing chb wall (the one facing the street). build up a frame on your wall using GI framing, then apply a layer of Rockwool insulation, then finish with either acoustic rated plasterboards or thick fiber cement boards. you may also put rockwool on your ceiling if the sound from outside comes through there.
best to have a TRUSTED contractor/carpenter do this (ie. someone you know personally).
i have had great success with rockwool when i renovated my room. very well worth it.
you may also build up a chb wall adjacent to your existing chb wall. this was how studios were made before AFAIK. there should be a blank space in between the old and new wall to "trap" the sound. takes up a lot of space though and would be very messy.
hope this helps!