Whats the safest way to put on weight&bulk up?

Eat more: Keep track of your calories. You must take in more calories then you burn. There is app for phones called myfitnesspal which can help you keep track of calories. Eat 6 smaller meals a day rather then 2-3 big meals. Have breakfast every morning. If you want healthy weight avoid fatty foods and try to eat healthy. Keep track of calories in and calories out.