- Check your brakes. Practise emergency stops in the park or similar before you go on the roads (the important thing is that if you slam the brakes on you will tend to go forwards; you need to learn to compensate for this when stopping. It's pretty straightforward in fact, but having a go at it before you actually need it is a Good Thing.).
- If you are ever going to cycle in the dark, have working lights and use them.
- Read the Highway Code. Cyclecraft is also a useful read.
- The rules of the road do also apply to cyclists. In particular: stopping at red lights, and not riding on the pavement (unless it's a designated cycle lane: see below).
Don't ride in the gutter
It will feel initially more scary, but it is much much safer to ride well out from the kerb. (I usually ride about a metre out, a bit less on narrower roads.). Reasons for this, in no particular order:
- Cars will in general give you the same amount of space that you give yourself. So if you are a foot from the kerb, they'll overtake with a foot to spare between them & you. If you're 3 feet out, they'll give you more like 3 feet of space. Which is Better.
- Gives you a safety zone of space to move into if something bad happens.
- Car drivers are concentrating their attention, broadly, on the bit of the road where they expect to see traffic (i.e. where the other cars are). If you're at the side of the road you are less likely to get noticed & more likely to be coded as "street furniture". Cycling where the cars go (about where the LH side of the cars go, is about right) means that you get treated as traffic. This is also safer.
- Gutters are where broken glass collects. Tyres do not like broken glass. Also there are bumpy bits of road & drains & other things that will send you off course.
- Pedestrians have a bad tendency to wander into the road at a moment's notice, or wave their arms around or whatever. Stay clear of 'em.
In fact, the general rule is that if you behave like traffic, you are more likely to get treated like traffic. Note: keeping out from the side of the road is particularly important when passing parked cars. You must be *at least* car door width out, otherwise some idiot will open a door into you. Further note: some cycle lanes are ludicrously narrow & would have you in the gutter. Ignore them.
Mirror, Signal, (mirror again), Manoeuvre
I got taught this when learning to drive. Obviously bikes do not have mirrors (well, they can do but I certainly don't). So substitute "look over appropriate shoulder". Leave plenty of time before you want to do whatever it is you are doing. Check over your shoulder (to ensure that there's not a lorry behind you which is about to take your arm off). Signal *clearly*. Just before actually executing the manoeuvre, check over your shoulder again (this is v important! Motorcyclists call it "the lifesaver", esp when turning right). Then move.
- Don't signal until & unless you really are ready to move, or you'll confuse people.
- It is however fine (& indeed correct) to delay your manoeuvre if you check over your shoulder & it transpires that it will be unsafe.
- Don't bother with the official slowing-down signal, no one knows it & it'll confuse people (just indicate L if you're going to stop at the kerb, & allow plenty of time to slow down if there's anyone behind you.).
(undertaking = overtaking on the inside i.e. the left). The Official Advice on this is "don't do it", however, that's a bit unrealistic. Do it with great caution, & only when there's plenty of space. Be wary for people opening car doors, pedestrians wandering between cars without looking, other cars turning across traffic queues without expecting you to be there.
DO NOT UNDERTAKE LONG VEHICLES. This is the biggest single cause of cyclist deaths in London. They may not be able to see you, and if they turn left or move inwards you wind up very very squished. In particular: do not stop alongside a long vehicle. Ahead of it or behind it, but not alongside it.
Cycle lanes & other facilities
These are not compulsory. If you think that sticking to the road would be safer/quicker/more convenient/whatever, then you are 100% entitled to do so.
Useful cycle facilities: bus lanes (nice & wide, occupied only by buses, bikes, taxis, & the occasional naughty motorbike; but do be aware that buses will stop frequently and you may wish to overtake); Advanced Stop Lines (those bike boxes at traffic light junctions so you can wait ahead of the traffic. Not always respected by traffic; in this case it is IMO acceptable to take yourself ahead of the ASL & stop right in front of the car at fault.); cycle lanes in parks if you fancy a nice gentle pootle; some cycle lanes which allow you to go the wrong way up one-way roads; some very few well-designed cycle lanes.
Useless-to-bad cycle facilities: the vast majority of cycle lanes. Which are overwhelmingly too narrow, stop/start at random, are full of crap & broken glass, encourage dangerous undertaking, etc etc. Avoid bike lanes on pavements if at all possible unless you enjoy pedestrian-slalom (pedestrians, sadly, are fitted with neither indicators nor brake lights). Be aware that cycle lanes may stop very suddenly & spit you back into traffic (see: Upper Thames St, among others). Use your judgement & if in doubt stick with the traffic.
(I also have a whole rant about the abstract concept of cycle lanes & why it sucks. But I shall leave that for now.)
Pay attention & think ahead
The correct assumption is not *quite* that everyone else on the roads is a dangerous moron, but you should expect people to do daft things & prepare accordingly. Keep your eyes open not only for what *is* going on, but for what might happen next (is that car going to pull out of that side street? etc). Catching the eye of drivers is a good way to make sure they've seen you (avoid the Sorry Mate I Didn't See You accident). Mostly this is road awareness & is something acquired by experience, but you'll pick it up quicker if you're aware that you *want* to acquire it.
As suggested below by mr_tom: good positioning is better than swerving. Look ahead and think about where you're going to want to be and what might happen in the meantime, and position yourself accordingly. It's better to move across the lane early & smoothly to go round an obstacle than to come up right behind it & have to turn sharply and slowly.
This is not so much a safety thing but an enjoyment thing. People will occasionally do stupid things. (Sometimes those people will be you). Try not to get worked up about it. Swear; compose brief but scathing letters to the press in your head; and then let it roll off you & think about what's happening next. See above re thinking ahead - this helps make things irritating rather than dangerous. But if you spend half your time fuming about bad behaviour, you won't enjoy the riding, & that's far more of a shame.
- Get a decent lock; ideally 2, of different types (e.g. D-lock & cable lock). Always lock frame + both wheels to something solid when leaving your bike on the street.
- Join the LCC - you get free 3rd party insurance and legal cover, and a nice green sticker. Plus they do cheap bike theft insurance if you want that.
- Get the appropriate London Cycle Guide maps (free from bike shops), as they are v useful.
- Consider learning to fix a puncture; although the maps mentioned above show where bike shops are.
- Helmets: some do, some don't. I don't. http://www.cyclehelmets.org/ may be of interest; make your own mind up. If you do, buy one that fits well & do it up properly or there really is no point in bothering.
If in doubt, feel free to stop, get off, & push for a bit. (e.g. at confusing junctions). There's nothing wrong with doing that. OTOH: try to work out what you *should* be doing at the confusing junction so you can give it a go next time, because otherwise you'll never manage it :-)
 If you're right behind the bus, you may be safer over towards its RH side, so you can see round it as it slows/stops. If you're a ways behind it, stay in the normal riding position but keep an eye on it, and if it indicates left and/or starts to slow, check over your shoulder and pull out to the right (sufficient to pass the bus) well in advance. You want to avoid coming to a stop right behind it and having to edge out into the traffic.
 Quick summary: it encourages drivers to see cyclists as a non-traffic nuisance, & we already *have* a perfectly good network of cycle routes which are called ROADS.
 The possible exception to this is commercial drivers where you may wish to note their company & reg no & write to the company complaining if they've been particularly bad (unfortunately I rarely do this because I've got too good at forgetting about incidents).