Water well and if needed water twice...once in the morning and once in the evening
Cover your plants with a shade net. If you don't have a green house no worries, use any old bedsheets or sarees and tie them up.
Solarise your soil, this is the time when you can rework your garden and deweed it.
Do not trim or cut down your trees in summer, they need the foliage.
Keep a container with water for the birds, squirrels to come have their fill.
Sow greens, they are the best to grow in summers.
Repair your trellises, re-paint your pots and stands.
Do not over fertilise your plants.
While spraying 3G please dilute 1:15 with water, the quantity of 3G to be used should be less. The heat and the oil in the 3G could burn the leaves in summer.
Water early morning's or late evening. Water deeply once a week...which means water till you see the water trickling out from the drain holes in the bottom of the pots.
Use materials like cocopeat, perlite, vermiculite which will help retain moisture in your pots.
Do not re-pot in summer.
Peppers, tomatoes, beans, cucumbers, courgettes, bitter gourds, okra, brinjal can all be grown in summer.
Keep your pots clustered together as a group.
Wilting, leaf curl are signs which say your plant needs more water.
Hope these points work for you.
Happy Growing!!!