Well, what you're doing is correct. Getting the feel of the airbrush and doing all those circles and lines is extremely important. Never run before you can walk!!!!
When you feel you have mastered that and you are not spraying wet get some tips and stick them onto a piece of paper with some blu-tack underneath. This will keep the tips in place while you airbrush them. Put your base coat on and wait for this to dry.
The next step that I teach on my courses is colour blending/fades :rainbow: (Just thought I'd use that for the colour blending effect!!!!!!). Try to fade similar colours into each other i.e. light blue to dark blue, light pink to dark pink etc. Always start off with the lighter colour as this will prevent you having to thoroughly clean the airbrush in between colours. Spray the paint diagonally across the nail starting on one corner and graduate the colour towards the middle. So with the light colour start off very light in the corner and get darker as you get more towards the centre. Then do the opposite with the dark colour - start in the opposite corner and spray very dark in that corner and lighten it up as you get towards the centre. This should look like the colour blends and fades across the nail. Then use an airbrush top coat.
It will take time to perfect this but keep practising - you will get there. When you think you've done that try 3 colour and 4 colour blends.
I hope this helps.