Going to a two-column format might look more visually appealing, but you’re forcing the reader’s eyes to pick a column when skimming a resume; best case scenario your primary content is in a dominantly-sized column (ie, on a 70/30 split or 80/20 split, their eyes are more likely to follow the larger block, but not always); worst case scenario is their eyes zig-zag across the columns and they don’t pick up a lot of relevant content.
Leave “areas of interest” off of your resume. Automated resume scanners might misinterpret your “C#/.NET” interest as an actual skill and incorrectly identify you as a developer in that area.
Don’t make your resume a huge wall-to-wall block of text; most people scanning your resume only spend 6 to 10 seconds looking it over for relevant information. If you’re writing your whole life story then you’re spending a lot of time writing something that few people will ever read.
Don’t explain common work experiences in non-technical jobs. As a hiring manager, it’s important for me to see that you’ve been employed, certainly, but if you worked at a fast-food restaurant as a cashier, I know 99% of your job already, you don’t need more than one bullet point to tell me you dealt with customers.