My experience with sticking key in ignition lock: be very careful there!
If you can really tell it is the steering lock that blocks it - ok, but then, indeed, as described below, just turning the steering wheel a bit before turning the key should help - it is quite normal.
But if it is the key is getting stuck in the tumbler - one should take it out and repair it as soon as possible. Someone said to me: if your key sticks once - take the lock out and fix it, do not wait because it will stick for good sooner or later. I ignored it and ended up on a lorry to take my car to the shop to fix it. Then it takes lots of blood, sweat, tears and distruction to remove ignition tumbler.
If you decide just to lubricate it a bit and see what happens - use a dry lubricant dedicated to tumblers! No WD40s or alikes. What waorks when you have nothing else at hand is to scrub a soft pencil against the cuts on the key. Graphite will lubricate it too.