How tall are you and what are your measurements? It's difficult to really recommend anything (or ascertain whether you actually need to lose weight) without knowing your height and frame. 70kg may be perfectly normal!
Either way, the best way to lose weight is to create a calorie deficit - i.e. ingest less calories than you use. Make sure that the calories that you do have are from nutritious, healthy sources (so 1500 calories from McDonalds are far worse than 1500 calories from fresh ingredients, cooked at home).
Spread your protein intake evenly throughout the day - it'll keep you full for longer and reduce your desire to snack. It'll also help you when you're exercising.
Snack on fresh fruit and nuts, lower your intake of simple carbs and sugars (so no fizzy drinks, minimal white bread/pasta/potatoes and stay away from sweets and cakes).
Eat plenty of meat and oily fish, and go nuts with salad. You can be pretty inventive if you're a good cook, This is the programme I'm currently on (started with my other half at the beginning of this week) - we have wholegrain banana and honey cupcakes for snacks, and I not know about 20 delicious chicken and salmon salads.