How do we lose weight? By getting less calories we need meaning that at the end of the day you have consumed less calories than you've burned. You shouldn't make it any more complicated than that. There are two things what you can do about it:
1. Adjust your nutrition so you'd get less calories a day than your TDEE is but more than your BMR is.
2. Burning more calories by doing more cardio.
TDEE= Daily calories needed to maintain current weight
BMR= Daily calories needed for your system to function
For optimal results I'd do both simply meaning for example I would watch what I eat leaving all the junk out and doing cardio daily and see what happens after some time, 1-2 weeks maybe. If I did lose weight I would continue doing that for 1-2 weeks again and see if I lost some weight again. At this point might be that I didn't lose weight meaning something has to be done. More cardio or cut out some calories.
Calorie calculator for tweaking(Indicative)=
http://scoobysworkshop.com/calorie-calculator/For cardio: Do what you like. Of course it will be more pleasant to do cardio which you like. I mean anything which rises your heart rate and keeps it there. HIIT is good if you like it(I myself prefer steady phased jogging over HIIT running), football and most of team sports have HIIT effect. Hill running is just great if you can keep doing it for preferably 0,5-1h. When to do cardio? It's also what you prefer.
