What to do in first year of a newly sown lawn

Last year (autumn) I killed, dug, levelled and re-seeded my lawn with good quality shade tolerant grass.

Success! It looks good. Its could do with being a bit denser, I get wheel tracks (flattened grass) after mowing that last a few days, and a few weeds are appearing but I'm happy.

What should I do now? Should I weed and feed, or feed, or water this year? I want to build on the good start.

David