We all have close shaves, most do not get reported, some are closer than others. In VFR-type flying there are some measures you can take to reduce the risk of a mid-air collision. Know the high risk areas - especially when joining a circuit. FAA research shows that most mid Air collisions occur within 3 NM of an airport, most happen at or below 1000' AGL. 'Areas of Operation' have been added to VFR charts in Ireland to assist in identifying such potential threats. EINC, Newcastle airfield - just south of Bray Co Wicklow, is a busy area for uncontrolled GA traffic operating VFR outside controlled airspace. It has an ATZ established - the only one to date in Ireland outside controlled airspace. Always look and listen out for other aircraft, especially when near an airfield; use the listening squawk system when en-route. https://www.iaa.ie/docs/default-source/misc/airspace-01062017.pdf?sfvrsn=2c5f07f3_0 Dublin CTA 118.500MHz Squawk 0401; Shannon CTA 127.500MHz squawk 2655
Use whatever means you have available to visually highlight yourself to others, make regular turns to expose blind spots (this may also highlight your aircraft to others). If you have a choice, dark colours are best for airborne visual conspicuity. Always have your anti-collision and strobe lights on - consider landing lights also when in the vicinity of an airfield. Always have your transponder switched ON with mode C (altitude) active.
Consider Electronic Conspicuity for your aircraft - ADSB in/out is the emerging future-proof technology. Portable devices and mobile app software are available; a study by GASCo into Human Factors associated with EC devices and some 'TOP TIPS for using EC devices' are linked below.
A VERY close shave occurred in the UK in 2019 involving 2 x light aircraft operating from the same airfield flying disabled children on local air experience flights. The AAIU summary below is well worth reading.
There were 2 GA fatal mid air collisions in the UK in 2011, both occurred in the vicinity of airfields and both involved aircraft re-joining the circuit, links below.
Other good material in the links below include the UK Airprox board website which has a wealth of material to help you avoid mid-air collisions.
The UK CAA 'Skyway code' has some excellent advice on lookout and avoiding Mid Air Collision.
A short brief on SkyEcho2, a portable ADSB in/out system, is below. 'Safesky' https://www.safesky.app/en is an excellent software app if you normally have data coverage on a mobile device while flying.
Finally, a link to an EASA website on How to avoid airspace infringement & reduce the risk of mid-air collision.