I too am hour building. It is important to fly as accuratly as possible at all times. +- 5 degrees on heading and +- 50ft on altitude would be good to aim for.
I try to go flying alone for an hour once a month and practice these:
1) 360 degree turns, maintaining altitude and airspeed (bang on)
2) Rate one turns.
3) Climbs and descents at specific airspeeds and rates of climb/descent and configuration
4) Climbing and descending turns, 15 degree angle of bank, at specific airspeeds and rates of climb/descent and configuration
5) Slow flight - 5kts above the stall. Climbs, turns etc.
6) Stalls
Every time I fly I practice for engine failure after takeoff, if not practically, then at least in my head. Memorise the checks.
The remainder of my flying is cross-country. I make very thorough plans and try to set myself objectives throughout the flight that I would like to achieve. For example, when landing away at an unfamiliar airfield, I found that my join and circuit wasn’t as good as it could be, so one flight was concentrated on perfecting it.
One other thing to consider if you are going commercial is not to perform checks that are too specific to your aircraft. Use FREDA and landing checks that can be transferred between all aircraft. A typical concern of mine is my landing check:
"Brakes off, landing gear down and fixed, mixture rich, carb heat warm, hatches and harnesses secure, carb heat cold."
There is an emphasis here on landing gear down and fixed - I fly a fixed gear aircraft, but won't always be. I've got that in to my head now, so there is less chance of cocking up later!
The most important thing for me is practising everything learnt from the PPL and applying it to as many different situations as possible. This involves moving away from your local area to unfamiliar places, encountering different terrain, weather, airspace etc..
Good luck
Bodie