The easiest way for short distances in the city centre. Not to get lost, you can take one of the paper maps available at the registration desk, or use your favourite map application on your phone. There is an interesting Czech application Mapy.cz [Android,iOS], which covers the whole world and allows you to download maps for offline use.
Prague has a very dense, affordable and quite reliable network of public transportation provided by the company DPP and based on the underground Metro and surface tram and bus lines. It also includes a couple of ferries and a funicular. Together with long-haul buses and local (S-lines) and fast trains it forms an integrated system called PID with the same tickets being valid in the whole area of the city.
The basic fare is 40 CZK (1.7 EUR) for 90 minutes ticket [all fares], which is valid not from the time of the purchase, but from the time it is validated (stamped). You need to stamp it the first time you enter the vehicle or the compulsory ticket area of the Metro. The tickets can be bought in vending machines and DPP or newspaper kiosks. Recently, it is also possible to pay directly in trams using a contact-less card payment. If you have access to mobile internet, perhaps the most convenient way is to use the application PID Lítačka, where you can search connections and purchase tickets.
Connection search is available in the PID Liítačka or several other mobile applications or on the DPP site.
Getting from the airport
You can use buses 119 or 100, which bring you to the closest Metro stops. They are part of PID and require just the standard tickets. There is also a special bus line called AirportExpress of the Czech Railways, where tickets are sold directly in the bus for 100 CZK.
Renting bikes and scooters
Several companies offer on-street renting of standard or electric bikes and electric scooters via mobile applications. They can be quite convenient way to get around, even if riding the very centre of the city with its narrow streets paved with cobblestones can be tricky.
Prague can be easily reached by car. However, it is recommended not to go in the very center. In the rush hours the traffic is slow and in general parking is quite difficult.
Parking in the streets is paid; there are two categories: blue zones that allow only short-term parking for non-residents (up to 3-4 h) and purple zones where a non-resident can stay up to one day. The Břehová street directly in front of the venue or the street parallel with the river are the purple ones, but it is quite costly, 60 CZK/h (2.4 EUR/h). During the weekends and nights it is for free. There is a mobile application MPLA.io [Android,iOS,web] to pay for the street parking, sometimes one can find also blue parking machines that sell paper tickets. Another option are private underground parking lots, for instance Rudolfinum (660 CZK/day), or another private parking like this: https://www.mrparkit.com/en. One can also park a bit further away and use the public transport to get to the venue. For instance Letna is not too far by tram or even on foot and it should be 400 CZK/day. General information about parking and a map of the street and some private parking can be found here.
Numerous companies offer taxi service in Prague, e.g. AAA, TickTack... The city sets the maximum allowed prices: 60 CZK to start a ride, 36 CZK/km and 7 CZK/miute of waiting time. In addition to the conventional taxis, there is also Uber and similar companies like Bolt, Liftago operating in Prague. More info can be found for example on this page.