Read the 1st chapter: this is good for a first shot! Don't worry about being a newbie, we all start somewhere.
My suggestion would be to use a bit more commas and, where you can, to paint a picture for the reader.
For example, instead of "Dean was instantly impressed with luxury cars" you could also say "Dean's wide eyes sparkled as his lips parted into a toothy grin. 'Wow! Wasn't expecting preferential treatment like this!'" (if you go this route, be careful not to overdo it. Sometimes it's fine just to tell the reader what's going on). You can also list names of the luxury cars in the room to add an element of realism. Keep writing and honing your craft!