First, welcome to the Guild!

I think you're on the right path, generally. You've taken a rough sketch and turned it into some fairly natural and workable landmasses, and you can't go wrong with the aged and folded paper approach.

Now for some critiquing:
1. If those brown lines in the landmasses are meant to be rivers, I think you need to rework them immensely. I'd go into further detail, but if those aren't rivers I don't want to belabor points you may already be aware of r.e. river placement and flow.
2. Right now your coastlines are very dark and almost pixelated in places. You might try using a medium to dark brown instead of black, and adding a slight (0.25-0.50) Gaussian blur to them.
3. I would choose a different parchment type background. This one seems to be a greatly expanded copy of an original that was much smaller. It looks messy and not-very-parchment-like when viewed at normal zoom. There are much better free parchment wallpapers and backgrounds floating around the intertubes. Alternatively, there are some good tutorials here and elsewhere on how to create your own parchment.

As far as scale goes, don't knock yourself out over it. There are several people here (Hai-Etlik in particular) who are extremely knowledgeable about actual cartography, but assuming you're not going for ultra-realism, you could stop at something as simple as a plain old scale bar. If you want detailed advice on graticules, scale, projections and the like, I highly encourage you to PM Hai-Etlik.

For country borders, I would say look at atlases, both current and historical, and see how geography, politics, and time frame help create borders. If you look at old maps of the Holy Roman Empire, for example, those borders are a nightmarish tangle based on intermarriage, feuds, trade quarrels, and a hundred other factors. Contrast that with maps of the USA, where wide open spaces and (relatively) few competitors led to lots of straight-line borders.

For color on your map, assuming you stay with an old-timey parchment look, I'd stay with muted, subdued colors, nothing garish and bright. Lots of browns, maybe some maroon and washed out blues and greens, depending on what you end up with. If the map turns out more political, concentrating more on borders vs natural features, then concentrate most of your color to helping pick out borders. If you want to focus more on terrain vs divisions and borders, then tone down the focus on the borders, keeping them simple, and concentrate most of your color and attention on the forests and mountains. If you want both, that's a little more tricky and the best thing I can tell you is to just keep experimenting until you get something you like.

Have fun, and good luck! And have some rep for jumping right in with the maps on your first post!