1. Paying for Photoshop to crop Instagram photos. Affinity (free) or Snapseed (free) does that. 2. Ignoring the RAW question. If you shoot RAW, you need a RAW engine, not a filter app. 3. Buying before trying the free tier. VSCO, Polarr, and Lightroom Mobile all have free tiers. Use them for a week. 4. Forgetting mobile versus desktop. LumaFusion is iPad-first; Affinity's iPad version is still coming. 5. Chasing AI features you will never use. Generative fill is fun twice. 6. Ignoring export formats. If your camera shoots HEIF and the app chokes on it, walk away. Convert problem files free with PicConvert. Sources: Adobe, Blackmagic Design 7. Renting what you could own. $22.99/month forever versus $49.99 once for Pixelmator Pro. Do the three-year math.