Besides good grammars, a very important element is your approach to study in general. For example, a few practical suggestions that have yielded tremendous benefits for my studies are:
1. Study when your mind is fresh. For me, this is in the early morning hours before the day takes its toll on me.
2. Carry around with you, either on paper or digitally in your cell phone, a running vocabulary list or paradigm list (which you can add to as you master them)
3. Throughout the day, repeat the words to yourself and try to formulate simple (even if incorrect) phrases in Greek. If you see an object at home or the office which you learned in Greek, then think it and say it. In short, use it or lose it . Correct grammar comes in time but the value of "thinking" in the language immediately can't be overstated.
4. Flash cards are helpful (essential I'd say) and there are also digital options with applications for PC, Mac and iOS that track your progress
5. Maintain consistency with your progress in small portions. Set goals but make them realistic lest you deflate yourself from discouragement in unmet expectations.
6. Limit yourself to study in realistic chunks of time. I'm a glutton for punishment, but not everyone should exaggerate the amount of time in one sitting of study, which can be counter productive if you overdo it.
There are many other things you can do, but I'd say think about a routine that will work for you and just go for it. Make adjustments as you go along.
Hope that helps.
Great ideas, thanks.