Hello there!
1. keep up to date with reading. read, and then read some more.. make notes on what you read, and have a good organised filing system of all the articles you have read and made notes on.
2. start writing early, even if it's just 10minutes a day.., even if it's not completely related to your phd.. you never know where your inspiration will come from.
3. keep your lab book or whatever, up to date! most important. set aside some time during the day to write up what you did that day. trust me, its so easy to forget and be faced with scraps pieces of notes and a vague idea, and thinking, oh yeh where did such and such go, i know i had it here somewhere.
and good luck