Of course the first question that arises is why colonize Venus? Aren't there much better bodies in the solar system? Especially the comparison with Mars is interesting.
Well, there are a couple of reasons why Venus is a very good place for colonization:
Venus and Earth are the only planets who are big enough to hold a serious athmosphere, but small enough that they didn't become gas giants. To put it in another way, they are heavy and cool enough to retain CO2, N2 and most importantly 02, but light and warm enough so that H2 doesn't accumulate.
Beside Earth and Venus there is just one body with these characteristics: Titan, which also has a thick atmosphere.
Mars is able to retain the quite heavy CO2 (but even that is slowly lost because solar radiation is breaking up CO2 molecules), but N2 and O2 would be split up by ultraviolet rays and lost to space. Because of this, there isn't any nitrogen on Mars - it probably evaporated completely into space. Imported or locally created oxygen is likely to also evaporate into space.
Venus on the other hand has large amounts of nitrogen in her atmosphere. Because oxygen is heavier than nitrogen, it is save to say it won't evaporate into space on Venus.
For colonization you need - just like for everything else - energy. On Venus, the Sun is 91% stronger than on earth, almost twice as strong. Plenty of energy for solar panels and plants.
In comparison, Sun shines on Mars at only 43% the intensity as on Earth. Solar cells are less than half as effective and plants grow much slower.
An advantage which is not essential, but comfortable is Venus' surface gravity of about 90% of Earth's.
On Mars' surface, gravity is only 38% as strong as on earth.
Although the idea of this website is the colonization of Venus, Venus also has a couple of disadvantages and problems, which of course have to be discussed.
Because of the missing magnetic field, the solar wind is directly hitting the atmosphere. This will possibly cause a higher overall background radiation.
On Venus there are with high probability active volcanos. It remains to be seen how much volcanos interfere with colonization.
On Earth, ultra-violet radiation from the sun breaks down water in the clouds, and hydrogen may escape to space. Because of the ozone-layer, the radiation is reduced and the effect small. So we won't run out of water on Earth anytime soon. On Venus, the radiation intensity is higher and there is no ozone-layer (yet), therefore the loss of hydrogen may be a problem. However further exact calculation is needed to determine wether this effect is neglectible (like on Earth) or not.
Because any attemt for colonization has to be done in the atmosphere, only elements from the atmosphere are available in abundance. Any other elements either have to be imported or there is a way to mine for them on the 480°C hot surface. Both is difficult and expensive. However, carbon-based materials have been discovered in the last decades that may replace not all, but quite a lot of metal. (for example carbon-fibre reinforced plastic is superior to metal in many applications)
On Venus, the day is 116 earth-days long. That means everything has to widthstand 58 days of uninterrupted solar radiation and heat and then 58 days shadow and cold.
However, on Earth the polar regions have even longer periods of light and day. Also plants have adapted quite well to seasons and very often are not active in winter.