While some basic fitness training is an excellent start for the novice hiker, there are one or two additional things that you really need to do before you set out on your first hike.
Even with the right pair of hiking boots, and a good pair of hiking socks to go with them, it's a wise idea to 'toughen up' your feet a little bit and, in particular, to concentrate on conditioning your soles. This isn't essential, but it's a sensible precaution to avoid problems.
Walking around the house barefoot for a few days before your first hike will help to some extent and many people believe in rubbing witch hazel onto their feet two or three times a day. There is also a cream known as Benzoin which can help with sores and will also toughen your feet over time. This is also an excellent addition to your backpack once you start hiking.
If you do run into blisters then this is really a subject all of its own but, as a very general guide, you should puncture any blisters to allow them to drain and then let nature takes its course before continuing with any training or hiking. As a preventative measure you can cover any areas that are likely to develop blisters with a band aid.
It's also helpful to keep toenails well trimmed, but don't trim them down too far or they can rub and puncture the skin, making walking extremely painful.
Build yourself up gradually. Even if you're in great shape, you should limit yourself to no more than five miles to start with and, if you're not quite so fit, then starting out with just a mile or two is fine. Hiking often entails walking over rough and uneven surfaces and you'll find that it requires a lot more effort than simply walking around town on paved paths. At this point, take only what you need with you and don't carry a backpack.
Once you're feeling comfortable and have made it up to around five miles you'll want to start getting used to hiking with a backpack. Again, take only what you absolutely need to start with, including water, and gradually add more 'convenience' items as you get used to the backpack.
You should always carry some form of mineral replacement food with you or, at the very least, a sports drink. Avoid sports drinks with lots of sugar though as, although sugar isn't necessarily as bad for you as many would have you believe, the form of sugar contained in many sports drinks doesn't always provide you with energy that you need for the best results.
If you're going to be hiking in an unfamiliar area, or going onto unmarked trails, you should always be accompanied by a knowledgeable guide or, if this is not possible, should at least take a map and compass (and possibly a GPS navigation unit) with you. These, however, are not going be much use to you unless you know how to use them and so you need to set some time aside during your preparation to learn the basic skills of map and compass work.
Whatever you do you don't want to get lost. The last thing you want is for your first real hike to graduate from a two-hour walk in the sunshine into a two-day search and rescue effort.
If you take things slowly and work up to longer, more difficult hikes gradually you'll enjoy the experience much more. The majority of people who give up because they get sore, injured, bug bitten and a host of other things do so because they tried to do too much too soon. If you exercise sensibly, take things slowly and use a little common sense you'll be a hiking expert in next to no time.