DAY 1
3 x 8-12 banded pull-ups. If you go over 12 move to a band with less resistance.
25 x Ring Row. Add 3-5 reps a week. If you can string together more than 10 in row make the movement more difficult by being more parallel with the floor or add a weight vest. 
25 x banded face-pulls. Add 3-5 reps a week.

DAY 2
5 × 5 Self-assisted pull-ups.
3 × 8-12 curls with barbell.
3 x 8-12 Behind the neck strict press.

DAY 3
5 × 2 Pull-up negatives.
3 x max hang from a pull bar with 1 minute rest.  
5 × 5 Self-assisted pull-ups.

Record your progress towards a strict pull-up.