Divisoria luckily has improved in terms of areas where you can shop. Air conditioned buildings now home what people usually would want to buy in "Divi" - affordable RTW and home goods and everything else you can think of. Yes, even pets.
One thing you might want to consider is the day and time you will to Divisoria. Best time to be there is at 9am just when all stores just opened. Also, take note that it is jampacked during weekends and holidays. No matter what time - so best to go during a regular weekday: Monday to Thursday.
Also, Divisoria is home to everything wholesale, buy something in bulk there so you can save a lot. Fabrics, materials for DIY projects, fruits and vegetables, locally made handicrafts, furnitures, toys, etc. I recommend researching where to get specific items so you wouldnt have to go around the entire area.
Lastly, enjoy great deals. Be open to shop where you pass. Divisoria is haven for bargain, its worth the effort, the sweat and good haggling skills.