I am currently correcting the same problem and have made some good progress.
I highly recommend this
This is a 5 part article series, it starts off explaining everything then gives you a few tests to run through and helps you choose corrective exercises.
With this type of problem there is no "one size fits all answer" but in general, this type of posture requires strengthening / activation of the glutes, lower traps,serratus Antrior, External Rotators (see external rotation exercises). You will also require some kind of soft tissue work for tight / overactive muscles wuch as pec minor, upper traps & levator scapulae, hip flexors, adductors.
This is very general but very common weaknesses. Basically you have lots of weak / inhibited muscles that need strengthened and you also have tight, over active muscles that need losened up, and some times lengthened i.e. upper traps / levator scapulae which help 'pull' your head forward.
Fix your day to day posture as well, shoulders down and back - chest out.
Sorry for rushed response and probably lots of typo's as well.