Create 10 practical strategies for retirement planning with ETFs that help private individuals in Germany build wealth over the long term and improve financial security in retirement.

Context: [retirement planning, ETFs, wealth building, Germany, Riester pension, ETF savings plan, returns, risk diversification, tax advantages, financial planning]

Goal: [efficient use of ETFs for retirement planning, selection of suitable ETFs, consideration of tax aspects, design of long-term savings plans, risk minimization]

For each strategy explain:
1) the specific approach or procedure for retirement planning with ETFs
2) practical tips for implementation and product selection
3) notes on opportunities, risks, and tax framework conditions in Germany

The strategies should:
- consider different types of investments and risk profiles
- address common ETF formats and savings plan models
- also include aspects such as Riester and Rürup pensions
- be suitable for beginners and advanced users
- contribute to sustainable financial security in old age