Use any available information to estimate slack or favorable current and time your passage or crossing for that period. Paddle in current under controlled conditions to familiarize yourself with its effect. Exercise caution when the current and wind direction oppose each other. Waves steepen and break heavily on shallows. Avoid those areas when waves are large or strong currents are forced to flow over them.
Waves steepen and break on beaches and shoals.
Generally, try to avoid landing in surf with a loaded kayak. Avoid surf on rocky beaches. Seas become chaotic. Cliffs limit landing sites and can cause chaotic rebound wave conditions. Make yourself visible and never assume you have been seen or have the right of way.