Since I don't know your experience level, I'm going to assume you've been doing it for some time, but not to the point where you would know everything you need to (intermediate skill). The actual isolation of the clothing to background is pretty much perfect (no white outlines where you would have missed parts of backing or part of the layer wasn't transparent), although on the North Face x Supreme image you do have that white-lining occurring. What I think it is, is you put on an inner glow or something so removing that would look somewhat better and not like a cut and glue type fashion on the image.
The font you used, no offense, is horrible. The font itself is ugly and your stroke on it is way too large.
In the backing try to have the foreground and background blend better, some basic options in layer styles can help with this if you mess around with them. If something goes wrong in one style you can either reset it or adjust it, very easy to work with.
Layer styles could help, although the way you executed them isn't the best, I'd say you're better off sticking to solid colour texts for everything and you can lower the opacity slightly so it's not as disctracting (opacity around 75-93, really just depends, play with it and see what you find you like).