NO SAND, NO SAND, NO SAND, AGAIN NO SAND I can't stress this enough, no sand. A good rich organic soil needs no sand, if you have clay soil, don't add sand, add organic matter, clay and sand become silt, which the worse kind of soil you can have, believe me, I have it and it's very difficult to work with as it holds very little in the way of moisture. So again, NO SAND!
Also, get the soil tested to see what if anything needs to be added, Your soil may just be fine the way it is. Barring anything worng, you can add composted pine needles, perlite(wash before handling), vermiculite, small sized bark chips dug in, manure, bone meal, blood meal. Opening new beds, do a double dig and rototill in your amendments. Check your acidity/alcalinaty levels and adjust accordingly. But please avoid using sand for drainage it can make things worse instead of better. In pots it's okay but not in planting beds that have high levels of clay.