Follow these simple six warmup exercises daily and you will find yourself a much much better guitarist.
1. "Spiders" help finger strength, finger speed, finger stamina and finger accuracy.
2. "Chords" help finger/hand strength, finger flexibility, hand speed and hand stamina
3. "Scales" help ear training, finger speed, finger accuracy
4. "Hammer/Pull" exercises help finger strength, finger speed, finger stamina
5. "String Bends" help hand strength, hand control and hand stamina
6. "Vibrato" helps hand stamina, hand control, hand flexibility and hand strength
in the following five posts i will show you these exercises. In order to help your control of the picking hand whether its fingerstyle or plectrum you can use the exercises above to aid you in that.
Also remember i have not discussed playing techniques as that is a field that is very vast and out of scope of this session. All that is here are just presentations of a few exercises that you can use now and again to keep getting better or to stay in shape.
If you have any questions regarding techniques or further clarification then post here and we'll get the answers with the help of others here at IGT.