I recall I would drink nearly a litre of water just before going for my chemo infusion so they could find the vein easier. I had a problem with my port, so they had to go in via my arm most times. Two ports ended up failing on me!
Another thing I did was each morning I would put a 2 litre jug full of water on my kitchen bench, that way I reminded myself to drink it! Most days I drank it all, and even on top of that I would have a couple of cups of tea or coffee. To this day I still often drink 2 litres of plain water each day.