1st get perfect kickbox technics then start doing shadow boxing and bag work out. What i do is daily 40-60 pushups every morning (as fast as you can), strech every day and powertraining 3 days a week. All other days martial arts.
Skipping rope is always good for cardio. If you are working out alone, start off with 100 kicks each leg for each type of kick that you know (i.e. front, roundhouse, side, spinning side, etc). Any footwork drills will help as well.
Some strength exercises you can try are: Using weighted gloves (no more than 3 lbs), go through all of your punching techniques. The reason that 3lbs is important is that if you go higher than that and you are snapping your technique (like you should), you run the risk of hyperextension or damaging tendons because of the trauma. Same thing for kicks. 2-3 lbs ankle weights or you run the risk of damaging your knees.