Already plenty of posts but thought I'd add my thoughts too
Amazon cheapie are fine. I use One Step OPKs and they have always been reliable. If you haven't a clue when you may ovulate, then start using them once af has done one. They're so cheap to buy plenty of it doesn't matter as much if you're wasting a few, and it's worth it to know when your surge happens. I usually use three daily; fmu, mid afternoon and mid evening. I have had positives mostly with evening but sometimes fmu too, although mostly fmu doesn't give a positive. I think what tends to happen is you have leftover lh with fmu, but everyone's different so it really depends on your body.
Fertility Friend looks like a nightmare to deal with but it isn't, it's actually simple once you have had a good look round and started entering in information. It usually needs a few cycles to recognise a pattern and start predicting with accuracy when it thinks af will arrive and when you're most likely to ovulate during your cycles.
You can temp orally or vaginally, I would recommend vaginally as its more accurate - you won't have to worry if you start talking in your sleep or snoring or sleeping with your mouth open, which can all alter temps. Just pop the thermometer in (not too far in!), wait for it to bleep then read it. Enter that reading into Fertility Friend and make sure it has the right time too, as sometimes for some reason, say if you went into the app at 1am, it keeps that time and logs it as the time you took your temp (or it does this to me sometimes!). Try to take your temperature at the same time each day, or as close to the same time as possible and don't do anything before you take your temp otherwise it can be inaccurate. Alcohol consumption can cause it to be higher I think, so bear this in mind if you have a glass of wine or something the night before. Lack of sleep can alter temps too, mine are usually higher the less sleep I have. Try to temp after at least 3-4 hours' sleep.
Temps are generally higher vaginally than orally, below 37 is generally ok for your follicular phase, but orally they can be as low as in the 35s, so there is quite a fair bit of difference between the two methods.
Whichever way you choose to temp, they should stay relatively low during your follicular phase, some people see a noticeable dip immediately before ovulation, some don't. The day after you ovulate you should see a marked increase in temperature, but this doesn't happen for everyone and sometimes it can take a few days for an increase to happen. If you notice this happening frequently but all other signs point to ovulation before the app pinpoints it, you can use manual override to put in your own ovulation day. The app likes to see three days of increased temps before it confirms ovulation, so it may not pinpoint it on the right day if you ovulate and your temp doesn't increase for a few days afterwards. You will get used to the subtle signs of ovulation over time and tracking though and should be able to pinpoint yourself when ovulation most likely happened whether or not the app gets it right.
Tracking cm is important because ideally, you should have either egg white cm or watery cm (bear in mind sometimes watery cm can be a sign of BV, so if it's excessively watery and outside of your fertile period, and accompanied by a strange or unpleasant smell, get tested for it. Self testing is cheap and easy and kits and treatment are available in chemists or places like Boots) when you're most fertile, and usually this is accompanied by a soft, high and open cervix immediately before ovulation, although position and feel can vary and you may find yours is like this a few days before ovulation, you may also find your cm is fertile a few days before, and it isn't uncommon for women to see a little fertile cm during their luteal phase too (although lots of it during your lp could indicate hormonal imbalance).
To check for this it's probably easiest to check internally, so reach up to your cervix and have a feel of that and make a mental note, and then gently try to scoop out a little cm and see what it looks like and if it can stretch between your fingers. If it's very stretchy and like egg whites then mark it down as ewcm, if there isn't any stretch and it's lotiony or creamy, mark it as creamy, if it's tacky and sticky, mark it as sticky and so on. If watery mark it as watery. If you're in doubt but think it's possibly fertile cm then mark it down as ewcm or watery, whichever is closest.
Try to check your cervix position and feel at the same time each day as it can change throughout the day.
Oh, and the cheap strip OPKs have to be as dark or darker to be positive (the test line). Once you have a positive OPK you should ovulate anywhere between that day or up to three days afterwards (three days is more unusual I think), so be sure to have plenty of sex during this time especially, and when you have fertile cm.
If you struggle to make fertile cm then taking evening primrose oil can help providing you aren't allergic, don't have any medical reason to avoid it (I think those with epilepsy should avoid it) and you don't take any medications which interact adversely with it. Drinking more water can also help with this too. If you really struggle, or if you just want some added help then a good sperm-friendly lubricant like Preseed or Conceive Plus can help. They're expensive but they're good. I found Preseed the best because it didn't sting me, and is the only one that doesn't do this to me, but I think my lady garden is weird so ...
If you don't already then take a good prenatal multivitamin, some extra B complex won't hurt too, and get your other half to take a multivitamin too to ensure good sperm health.
Also, if you see dips in your luteal phase don't worry about it. Could be implantation, or it could just be a luteal phase dip which happens sometimes and isn't unusual. The thing to watch out for are consistent high temps during your follicular phase, or consistent low temps during your luteal phase, which can indicate hormonal imbalances. The odd dip is fine, but if they are generally low and/or they start to really drop very early on then talk to your doctor about it. Likewise, if you feel your follicular phase temps are way too high all the time without any obvious cause, then talk to your doctor and show them your charts. Ideally, in your lp you don't want to see your temps dropping before 12dpo. Even if you don't get af at that time, if they're too low too soon then it could indicate low progesterone which can make implantation and keeping the baby impossible as sufficient progesterone is required from your body before the placenta takes over at 10-12 weeks gestation to support pregnancy. If you're not providing this then the pregnancy probably won't survive and for this you would likely need supplementation, although sometimes these things can be fixed through diet, exercise, general lifestyle, reducing stress and also using alternative therapies like acupuncture or reflexology. Just something to keep in mind as although I'm sure you won't have a problem, hormonal imbalances these days aren't hugely uncommon because most of us lead relatively stressful lifestyles and for other reasons too. Stress is important to deal with, as cortisol steals progesterone.
My signs that I ovulated are my cervix changes from soft and open to a little firmer and less open and also my cm immediately changes, literally the day I ovulate to creamy in consistency 99% of the time. With more water and taking EPO I have now been able to achieve ewcm in my fertile days leading up to ovulation which is fab. But this changes quickly when I ovulate, or immediately after ovulation. Most of the time I see a temp increase, but sometimes it isn't by much, and there's been the odd occasion my temps haven't increased immediately after.
You may also notice ovulation pains, a little like af cramps sometimes, sometimes they're mild and barely noticeable, sometimes they're quite strong. They can be centred or to one side, or both. You may not have this, or you may have it with some cycles but not all. I usually have ovulation pains a day or so before, starting quite central, then on the day they're usually to one side. These pains can sometimes last for days after ovulation too, so sometimes it's confusing especially if you don't have any other obvious signs of ovulation on a specific day or if your temps don't behave
Not entirely sure what I'm looking for on said chart or when recording CM...
I've seen people mention them on here, but as I've never charted everything sounds completely alien to me 
instead.. but just incase!
