We know of no organised tours to Guinea.
We know of no birding guides in Guinea.
There is a single trip report at Surfbirds submitted by Mary Crickmore and information about her trip is included in the hotspots section.
The cool, dry period between November and February is possibly the best time to visit. Independent travellers can fly direct to Guinea from Europe by a number of airlines, and Conakry is connected by air to other capital cities in West Africa. Bush taxi, bus and minibus operate between Guinea and neighbouring countries. There are domestic air services from Conakry to a number of towns and private buses operate throughout the country.
A number of travel issues are similar to those for any other African country. Guidebooks, travel companies and the above websites provide much of the advice one needs, but some key points warrant repetition here. (1) be aware of the risk of malaria, seek current advice, sleep in a sealed tent or under a net and take prophylaxis as recommended. (2) always ensure you have sufficient water and some method of purification (even if this comprises a pot and a campfire for boiling). (3) do not under-estimate the danger of being in the sun too long. Ensure you use sun-block and drink plenty of water, and wear a hat. (4) The incidence of Aids is high (5) Ensure that you take a reasonably-equipped first-aid pack with you including a supply of hypodermic needles.