There are pretty spreadsheets, there are great spreadsheets, and rarely, both together.
To me a great spreadsheet is supremely functional and very easily delivers what you want.
The more you do this the better you get.
1) Start with what you want to achieve clearly in mind
2) You should only have to enter the bare minimum into as few cells as possible. Everything else should then be pulled in by the spreadsheet using, for example, Lookup or Index, and calculated providing you the answer.
3) Routine repetitive stuff should be automated using the macro recording function.
4) If you get stuck at any point, just google what you are trying to achieve, there are wonderful resources on the net with great formulas suggested.
That's all you need to do, visualise what it would be in a perfect world, then work step by step towards it. The more you do this the better you will get.
If you are going to read about it, do so only to get ideas re what is possible.