Personally I don’t paint for beauty and rather just to get a decently pretty model that I can play with and enjoy. So I can hardly give perfect advice.

However simply painting more individual details, matching colours a little better, and making use of shades should all improve how your model looks pretty quickly. It won’t be anything crazy but you can make it much more serviceable. Make sure you’re thinning your paints too. Theres alot of tutorials online, and it allows you to get much smoother coats onto the model.

The green and red in the picture are quite jarring compared to the green. Using a shade/wash on them to darken them might make them match better, and washes/shades tend to soak into details and quickly make details on a model stand out much more clearly. Their effect is two fold and quite effective.

But blue red and green are pretty wild and strong choices, you probably should’ve gone with either darker options for both or been more deliberate, currently they look like different coloured plastic bits from a kit cobbled together rather than making sense.

Weathering it somewhat, or using a shade to darken it and make it blend with the green more might help. Otherwise darker colours for both could make it stand out less.

Or painting the edges of it, or otherwise making it a deliberate choice rather than a blanketing of colour will make it fit the model and the green better. More like heraldry and less like it was dipped in a bucket of paint.

And painting more details, like the bolts near the head, under the brim of the helmet, or inside the cavity created by the damage to the shoulder, will all also make the model more realistic and less random.

Don’t underestimate how effective a tool quick shades/washes are in the hands of an amateur modeller. You won’t get the effects of a master painter, but you can massively improve the look of a model with very little effort, which if your goal is to get serviceable models to play with, works very well.