In my experience, primer is almost as much as paint. So when I recently repainted the house, I didn't use primer. The biggest thing is check for existing cracking and pealing paint. Scrape and sand it off. It's a pain, but if you don't do it then your new paint job won't last. Also, don't use dark colors like brown. It makes your house look smaller and dingier. We used a creme for the main color and terra cotta color for the trim. Looks much better now 🙂