How much smaller than Earth? Scale is critical to getting mountains and rivers right.

For worlds much smaller than Earth (not that we have many examples), tectonics are unlikely to play a big part because the planet cools quickly. With lots of water (difficult with a small world because it's hard to hold onto those small molecules without a lot of gravity), I would expect to see a low, eroded terrain with possible volcanic areas not necessarily grouped into mountain ranges.

If you goal is "be just like Earth, but smaller" then you've likely got a workable result, subject to the question of map scale.

Having a hemisphere that's not ocean and one that is will likely result in some hideously dry interior regions, especially with it being polar. Pangaea here on Earth seems to have had vast, permanent interior deserts very much drier than even the depths of the Sahara or Gobi today. A huge polar contnent would make for some very interesting effects if there's much of an axial tilt. Temperatures in summer would get incredibly hot and in winter incredibly cold. A circumpolar jet stream might well keep out any moisture that does get pulled poleward from the equator. The coastal regions might be subject to massive monsoon effect, with big storms in spring and summer and a long (very) dry spell in winter.

As far as tools to get good mountains, it really depends very much on the scale of your map. "Realistic" mountains on a map 5000 km across will look very different from one 20000 km across, which will look different again from one 40000 km across. Similarly, a volcanic province will have mountains quite a bit different in appearance than an old folded range, which is again different than a young tilted block (approximately the Andes in South America, Urals at the boundary of Europe and Russia, and Sierra Nevada in westerns North America).