I just carry around a little journal and make myself write down EVERYTHING I eat and drink. Yes, everything. Including the calorie count. And then if I don't know how many calories were in something, I look it up online later in the evening when I have some time. Obviously this isn't a great way to count calories as it can be inaccurate, but I try really hard and I'm honest with myself about the portions.
This really helped me in the beginning because it made me realize just how much food I was eating. I hadn't been honest with myself about this in the past. It holds you accountable to yourself.
Also, this is going to sound very silly, but I'm a pretty lazy person. Sometimes, if I'm out or something, I can avoid eating because I know I'm going to have to look it up, figure out the portions (sometimes I even save the container a smoothie, etc came in so I can portion it out later), and write it down. It's not a lot of work but inconvenient if I have a lot of things to do.
I am by no means a weight loss expert but this little journal has been the key to the weight I have lost thus far.