It has to be something real specific such as instead of saying "I want to lose weight", something more specific would be "I want to lose 30 pounds".
...or refined even further you might say,
"I am easily and effortlessly weighing 130 lb." (Insert your desired weight)
You want to place your attention on the end result. Focus on what you want in the present moment. It can't be in the future or in the past. And while creating your desired self-image, feel the feelings you would feel while experiencing your new weight.
I've found though that manifesting solid objects that I can feel or touch is easier than manifesting a relationship or friendship
In NLP, the "feel or touch" is kinesthetic. This means that part of your strategy for manifestation has an outter "feel or touch". Without getting into a whole lot of NLP lingo, which won't help anyways, consider that the "feeling or touch" should be a part of your visualization.
When you close your eyes and create the image (through your own eyes) of your ideal weight, make sure to move your hands around to "feel and touch" the new you.