Learn to use Levels, adjustments and blend colours for retro results
Start off by increasing the brightness and contrast of your photo by going to Enhance>Adjust Lighting>Brightness/Contrast. This will give your picture a simple all-over boost before you start adding colours into the mix.
Head to Levels by hitting Cmd/Ctrl+L. With the drop-down Channel menu, pick the individual RGB strands in turn and move the middle stopper to 1.5 for Red, 1.3 for Green and 0.8 for Blue. This will add a subtle lomo effect to the picture, ready for recolouring later.
Click on the ‘Create new fill layer’ icon, and choose Solid Color. Pick any colour and click OK, set layer to Lighten and double-click on the layer preview again before selecting a dark pink (we chose #523b46). This adds a block colour over the darker shades.
Now it’s time to get creative with your gradients. Pick bright blues, pinks, greens and oranges for your gradients and drag them over your image on new layers beneath the Fill Layer. Add masks and drag monochrome gradients to fade the colour.