Hi, here is a gude from the cleanyourcar.co.uk website with details on how get then preserve the perfect shine on your car.
1. Pre wash with Snowfoam to loosen dirt.
2. Wash with a dedicated Car Shampoo using a lambswool/microfibre mitt (Sponges cause scratches) and two buckets with grit guards (1 for rinsing your dirty mitt)
3. Clay. Deep clean your paint using clay bar and lubricant (dedicated or weak soapy solution). paint will feel like glass after this process.
4. Polish (These stages are usually done with a polishing maching. Either a rotary or dual action polisher)
a. Restore. Restore dull, faded and negected paint with an aggressive polish known as a compound. (This stage would normally be carried out by a professional)
b. Enhance. Remove Light swirls and scratches to enhance the gloss of the paint
c. Finish ultra finishing polishes to give your car that showroom finish
Normally b or c is all that is needed for a perfect finish
5. Protect. Sealants and/or Waxes. Protect your finish with acryllic polymer sealants or waxes.
This is just a basic guide as Detailing is a minefield and personal preferences are abound.
Cleaning and detailing your Astra.