Make starting feel possible
Opening a large art set can feel exciting, then oddly intimidating when you do not know where to begin. Choose a small first project, such as a leaf or a simple colour study. Let that project decide the materials instead of buying everything at once.
Paper changes the experience
Hot-pressed watercolour paper is smoother; cold-pressed paper has more texture. Winsor & Newton explains these differences in its paper guide. Neither label guarantees a better picture. Think about the marks you want to try and choose paper intended for watercolour rather than treating any notebook as equivalent.
Make a small colour chart
Paint a sample of each colour and a few mixtures on the paper you will use. Notice how much water your brush carries and let samples dry before comparing them. We have not tested a particular set; this is a way to learn your own materials.
Buy the next thing after a few paintings
Keep a note of what actually limited the project: paper size, brush control or a colour you could not mix. Purchase around that specific need. A kit that is easy to set out and put away often gives you more chances to practise than a larger collection.