Not bad at all, for a first attempt! The one that stick out for me is #1, except the fact that the sandwich is cut off badly on the right of the frame. It doesn't feel intentional, but just slightly out of frame, and leads the eye over the edge. At least, that's my opinion. Other than that though, #1 is great. The sandwich is is well layered and the cheese cut into thirds makes the viewer acknowledge the food, even on a subconscious level. (making a viewer acknowledge something as simple as a plain sandwich is tricky in food photography, so kudos. Even if you didn't do it intentionally, I never would have thought of it haha)
#2 doesn't have the same punch. The sandwich's position of the lettuce worked better when in a distinct layer like in #1. Hanging over the cheese makes the lettuce blend into the cheese's layer, and I find that distracting... since a perfect sandwich is layers of stuff... also why I find my subway sandwich, with its blended layers, depressing when compared to the commercial for the same sandwich but the pro doing the commercial made the sucker a layered- dagwood dream sandwich for it! But I do like the addition of the tomatoes, makes it even more tasty looking. However, the sliced tomato w/ knife in the background is too distracting now that you increased the depth of field... I'd keep it shallow, to keep the information on the subject (the sandwich).
#3 Is the weakest of the series here, mainly because of the light. It feels less exposed than the other two, and the bread has taken on a darker tone, or perhaps it was the removal of the white cutting board, either way, it isn't as appealing to me as the first two. Also, seeing two halves of the sandwich -one on the other- against wood background on a glass plate is fairly boring to me, unlike the other two photos that have enough going on that it feels interesting. Plus the addition of the cutting board/knife/tomato made the sandwich feel even more "fresh" in #1 & #2, made you know it was just made.
Of course, this is just MY opinion. Take it for what you feel it is worth.
Overall, I think you did a great job! Especially never having done it before! Food photography is often considered one of the more challenging forms of photography, but I think you did exceptionally and should have no issue honing your skills.
If you are serious about food photography, and I were you, I'd also study some professional food photographer's photos. I know that they use a ton of tricks and secrets to stay on top in a competitive (moreso than even the usual for photo) form of photography, but by studying their work, you should then try to replicate it - using your own creative bag of tricks you'll have to figure out - and then work on going even further beyond it.
And, from what I understand, it pays off if you get noticed. I know a quote from when I was in College: something along the lines of "A well recommended food photographer is also very well fed". Meaning that the paid, professional food photogs make a decent penny for their skills. (not sure if it is true or not though).
