Flashcards and substitutional tables
I would suggest two types of activities
-o- Substitutional tables
On a sheet of paper (you can as well do this in your word processor), paint a table for a given sentence pattern, for example:
subject_____verb______object1_____object2______adverb
-----------------------------------------------------------
he__________loves_____parties__________________at midnight
my dog______brought___a bone______to me_______yesterday
etc.
Of course, although the words in my example are English, you should use words in your target language.
Use this table playfully and make all possible combinations. The silliest the sentences, the better!
This method is very useful to get exposure to the vocabulary, especially if you are learning an inflected language, like German or Russian.
-o- Flashcards
Instead of using paper flashcards, you can use them on your PC and let a "flashcard trainer" sort them out for you.
The ones you know well should be set apart, so you can progressively concentrate on the more difficult flashcards.
I recommend VTrain (Vocabulary Trainer), which seems to be quite popular among universities. It includes a scheduling facility that keeps the number of necessary repetitions to a minimum.
You can download it from
http://www.vtrain.net/home.htm
Good luck!