1. Tourism is a very important industry in Turkey and is a major foreign exchange earner. Therefore, it has an extensive network of trained tour operators who can help visitors to make travel plans and transport and hotel booking arrangements.
If you plan to tour the country which includes trips outside Istanbul, it is best to engage a tour operator registered with the Turkish authorities to help you (especially for the portion outside Istanbul) if you cannot find something suitable from travel agents in your own country.
The tour operator may not have offices in all the locations you wish to visit and may not have the specific tours you desire in each location, but through their connections, they may be able to pull together local tours offered by other operators to create an itinerary that suits your needs.
This should save you hassle, wasted time and frustration, as there are language barriers and uncertainties in a foreign country, although no doubt you have to pay for their services. Their charges are not necessarily shown separately as they may be built into the transport and hotel charges booked for you, but you can try to get quotes from more than one tour operator and compare the total prices quoted.
If you have to pay the tour operator some money for the bookings prior to departure, you should establish their trustworthiness by talking to them in person (on the phone) and by verifying their registration status with the Turkish authorities, especially if you do not find them through your friends or trusted travel publications.
2. English language is generally not be a problem in Istanbul because there are enough people around to ask. However, outside Istanbul and away from areas serving foreign visitors there are occasions when you wish you know some Turkish.
3. Money changing is not a problem, as there are money changers and banks in many places. Outside Istanbul, you may find them at bus terminals and airports and in banks in some towns, but it is wise before moving from one stop to the next to see if you need more cash and get them before moving on.
Money changers tend to offer better rates than banks, but compare. Also, you should find out if commission is charge on top of the quoted exchange rate.
4. Drink lots of water and use sunblocks. One should be careful with dehydration, if travelling is done in the hot seasons and if visits to the ancient ruins are part of the itinerary as the ruins are in the open and require long walks. Use a good dose of sunblocks and bring along something to avoid sun burns.
Drink only bottled water. They are reasonably priced.
5. Sanitary condition in public toilets are said by some to be not up to standard, but this was not a big problem (although could be improved) in Istanbul and nearly 15 other places in the country visited in mid-2008. However, be prepared to bring enough money as all public toilets charge a fee (as high as one Euro in some places).
6. Food is generally clean, but it is wise to avoid uncooked food, including salads and opened fruits.