I'm not trying to lose any weight as I am, but rather trying not to put any more on, and all I've been doing to avoid that is walking in the mornings and evenings, keeping track of water and limiting snacks. I can't go without any junk food, I'm too weak for that, but limiting it is the key (in my experience). It sounds silly but things like counting how many chips you're eating and making sure not to go over the single serving is proving to be really helpful (because we all crave sugar sometimes...).
If, however, you're looking to avoid junk food altogether (for which I must applaud you - that is a brave action and something I could never will myself to do) then I recommend trying out things like Glume mentioned, try to satisfy that craving with something more on the healthy side that still tastes really good.
Ah, I would also be careful with fruits."Fruits are chock-full of nutrients like vitamins, minerals, dietary fibre and phytonutrients, which help us stay healthy and even reduce the risk of disease" so please remember to eat them haha, but also keep your fruit range wide and don't stick to one type, because that could potentially be bad for you. Apparently.

My advice is only from experience, and from what other people have passed onto me, so if anything doesn't work for you I want to apologise in advance.