Take your temp at the same time in the morning. It's affected far more by time of day than by interruptions in your sleep. If you take the temp more than 30 min outside your usual time you need to note that and/or discard it if it's WAY out of trend. If you need to get up to pee, try and do it in the dark as much as possible (maybe get a nightlight), it'll disturb your temp less. I pee like a million times a night and it doesn't seem to skew my charts too much as long as I do it quick and don't turn on the full bathroom light.
Don't worry if your first few charts are a mess, it takes a bit to get the hang of it! I temp vaginally, it's not for everyone but I find it gives me a much steadier result than orally.
Do join FertilityFriend, it's free and they have a huge FAQ on how to chart properly. The notebook beside the bed is a good idea, there are also bbt thermometers that will save your temp for you so you don't have to remember it. I highly recommend the book Taking Charge of Your Fertility by Toni Weschler, it's the bible of all things charting.
GL!

