When I was learning english I was picking 5 verbs by day and I was trying to learn them before sleeping, and the sunday I was trying to remember them all. I learned a lot of new verbs and words like that ! And to keep your french "fresh" I recommand you to read some french everyday (maybe the news or whatever) just a bit of french everyday can do a HUGE difference in a few months !
I have learnt all my verb tables through stupid songs we're taught in school.
And after that its just a case of memorising.