A metronome is designed to program your note count in time. Once your on count it can get old, but can't be beat for picking techniques, especially when string skipping is involved. A drum machine brings life to your playing. I also highly recommend the investment. One song that really helped me on count, whether you like their music or not, is Black Sabbath "Fairies Wear Boots".
The "Time Keeper" (Bill Ward, in case they are too old for some younger players to know) is completely insane in this song. The changes in tempo are an incredible kick-ass count in perfect time. I imagine Ward literally destroying a Little 5 piece studio set while recording this song. I still play it on occasion.