I think besides completing your homework everyday and reflecting on what you've learnt that day, it's important to spend at least another 2hours of effective study. You can slowly increase the study time as you get used to it. Although people study with different effectivity, putting in the hours does help, it will train you to be able to sit still and concentrate for longer periods of time, as some of the HSC exams go for 3hours. I do not recommend studying every second of the day, unless that's an effective method for you, otherwise you'll just burn out and lose your motivation and fail in the end.
For me, I sometimes study in the morning before school if I have nothing better to do. Often, if I'm travelling to school alone, I reflect on what I've learnt throughout the week and what I should expect to learn that day. After school, I go to my local library and stay there to do homework and revision until the library closes (about 3.5hrs there). Then home, dinner, shower, chores, and squeeze about another 1.5hours revision before sleep. On the weekends and during holidays I try to follow the same routine as during regular school days, with the exception of Saturday afternoons coz I have sport (I find that if my motivation to maintain fitness goes up, so does my motivation to study). In the few weeks leading to exams and during exam period I up the hours of study and follow a more intense routine. This works for me. Set up your own suitable routine and stick to it!
Now, in relation to UAI estimates, punching your report marks in isn't very accurate. It's best to go by ranking. You'll find that generally, if you compare the final HSC marks obtained by students in previous years and their school rankings, there is little difference. Hence, if you find out the final HSC marks of a student from the last three years with the same ranking as you now and plug that mark into estimator, you'll get a much more accurate estimation.
For example, you may be ranked 60/160 for MathsX1. You find out what final HSC mark previous students of the same rank in your school got and average it. In this case, that may be 45/50. Do the same for other subjects and put in these HSC marks into estimator and voila! You have a moderately accurate UAI estimate.