There are two skills you need in order to master a manual transmission:
You can learn to heel-and-toe for getting going on hills where your right heel is on the accelerator and the right ball of the foot is one the brakes. Use your heel to get the engine revs up then release the brakes as you get going. In a lot of cases, you can use the parking brake to do the same thing - raise the revs and release the brake. You can learn to do it smoothly.
To down shift, you should double-clutch (or as the English say it, double-declutch). To do this, for, say, a shift from fifth to fourth, push the clutch and get out of fifth then rev the engine in neutral to where the revs would be in fourth then push the clutch again and go into fourth. This relieves the load on the synchronizers and enables faster shifting with less synchronizer wear. In old British sports cars with no synchro on first, it was the only way to downshift from second to first. We don't have many traffic circles / roundabouts here but there is nothing as satisfying as approaching a roundabout, double-clutching and going down a gear then accelerating out of the roundabout in the lower gear.