This information is not meant to encourage anyone to travel to Yemen (with the exception of Socotra Island) due to the current conflict.
Before you go: You must obtain a visa before you travel to Yemen. Apparently, visas are currently denied to individual travellers, so you will need the assistance of a local agency to secure your visa – this will be expensive if you do not use their services. I found ATMs to be a bit sparse, so bring cash with you when travelling through the country – Euros and US Dollars are probably the best. Yemen is a conservative country, so carry clothes that cover your arms and legs – this applies to both men and women. Women should wear a headscarf, which even by Yemeni standards would be considered modern as the overhwelming majority of women wear the face-covering niqab.
Accommodation: Because I only stayed in Sana’a and did not sleep in other places outside of the city, my experience is limited. There appears to be a wide variation on offer in Sana’a. It is far better to stay in Old Sana’a instead of the infinitely less charming new portion of the city. I chose the Dawood Hotel and found it to be excellent, though power was not always regular, but this is standard for the area. There are several other options in the Old City, some (such as the Burj al Salam) are more expensive than others. Check reviews on Tripadvisor for the different options that are currently available. Haggling on room prices is acceptable.
Food: I found the food to be of good quality overall, especially the breakfasts with traditional bread as its base. If away from the modern area of Sana’a, you are unlikely to find Western styled food options. Falafels and various other staple fares from the Arabian Peninsula, including some spicy Yemeni alternatives, are on offer.
Transport and Permits: You will be a bit restricted when travelling due to the need for you to obtain permits when leaving Sana’a. As such permits are required in advance, you will need to allow a day or more to obtain the necessary paperwork. It is likely that any transport you will undertake will be taken with either a privately hired taxi, tour car or by plane. It is also possible to travel on buses, but I have no direct experience of them so cannot comment on their quality.