Storage is a one-time decision
Most phones do not accept a memory card. Choose storage for the photos, videos, apps and offline media you keep, not for the amount you use today. A larger base model can be cheaper than upgrading later.
Update support is part of the price
A phone that receives security updates for longer can be the cheaper long-term purchase. Check the promised operating-system and security-update window for the exact model.
Battery and charging
Battery capacity is only a starting point; screen size, chip efficiency and software matter. Check the charging speed and whether a charger is included in the box.
Camera hardware and software
Sensor size, lens type, optical zoom and video recording are different from a high megapixel count. Look at the camera you will use, not the number on the spec sheet.
Buy the model, not the advert
Retailer bundles, trade-in values and carrier instalments change the effective price. Compare the total cost of the handset and the plan, not the monthly headline.