Health & movement. Avoid obesity, tobacco, and standing or sitting immobile for more than a couple of hours. It 'trapped', such as when flying, pump your calf muscles by contracting and relaxing them a few minutes every hour or two and/or take a walk down the aisle. Compression stockings may be helpful, particularly for specific risks such as varicose veins. It is uncertain if there is any benefit from aspirin.
Treatment. If you have superficial venous reflux then you should have treatment for this. You can have an ultrasound to find out.