Well i've been at it for over 3 years and took me about 3 years to be qualified as "good". Even though, i still have little things i'd want to improve here and there.

It takes alot of practice. Practice is your best bet for designing. The more you work in PS, the more you'll learn and the better you'll be.

Here are some pointers.

Start by looking around for some templates you like. Once you've found some, try and replicate them. (Don't take any credit or try to sell them afterwards. Do this only for practice and to learn some things.)

Find yourself a style and work on it to get your style to perfection.

Try to be original and unique with your designs.

Make sure to always have a nice color scheme. (very important, in the top things to remember for designing)

Use shapes, don't always go with squares or circles. Make variations because it makes it interresting.

Don't try and do like everybody else does, do what you like and be yourself.

Take advice from others and work on what they say. Some times critics can be very hard, but its the best thing to help a new designer. I know, i've been through it and it has helped be greatly!

I hope this tips will help you. If you have any questions, contact me via pms.