I got to Pushkin by an organized halfday-bustour from our river-ship-company and the total price was about 50 euros and included the entrancefees to the palace.
There was almost no waitingtime at the palace, and we passed by a long queue of waiting tourists, who came on their own.
Just a few days before I was offered such a tour in a private taxi for a total of 100 euros just for the VW-bus with a total of 8 seats and then it would have costed as well 50 euros extra per prerson for the entrancefee and guided tour through the palace.
This "Pushkin-parktrain" might be a good solution to see ALL of the park around the famous palace. In fact I did not take it, but just saw it passing by. It seems to be mainly for the russian tourists, because organized bustours will never give you enough time to take that parktrain. And when its mainly for the local tourists it will be quite cheap as well.
The easy way to get here is by taxi or those minibuses service they have. Not very comfortable and you are not always sure where they actually taking you unless you have a local guide as I did ;-)
I know you can also get here by train as well.
From St. Petersburg you can either catch a train at Vitesk Station straight to Detskoe Selo as the Pushkin train station is called. Not all the stops have easy to spot signs but it's the 8th stop.
The other option is to take the metro to Moskovskaya. Coming out of the metro station take the first steps to your right, then cross the small section of the park (on this big square) diagonally to your right. And a bit further on alongside the street with the buildings you find the marshrutkas for Pushkin. Make sure you take one that takes you right to Catherine's Palace (well round the corner). The cost for this journey is about 25 roubles.
The third option is the metro to Kupchino and then the train (elektritshka) to Detskoe Selo.
From St Petersburg, we got the train out to the station Detskoe Selo, and then got in the minibus from there to the palace. There are plenty of minibuses waiting there that will take you to the palace.
To get to Tsarskoe Selo - town of Pushkin is situated 24 kilometers from St.- Petersburg to the South on the Izhorskaya height, raising 150 - 160 meters above the sea level.
the best way is to take the local suburban train from Pushkinskaya Station in St.Petersburg.
I think the trip takes just under an hour if I remember correctly.
If you want to use public transports there are several ways to go to Pusjkin. Either you take the blue metro-line to Moskovskaya and close to the metrostation you can find minibuses with signs (mostly handwritten) indicating that they're going to Pusjkin.
We took the metro+minibus to go there, but on our way back to St Petersburg we took the local electrical train - elektritchka - from the train station in Pusjkin. The price is only a few rubles.
I arranged for a car & driver through Patriarshy Dom Tours. They offer a wide varierty of tours in Moscow (with a good reputation) and will also help to arrange guides, cars and other items in St. Petersburg.
The driver, Natasha, spoke little English, but I had written our destinations in Cyrillic, and we made out just fine. She was prompt, polite and even pointed out other buildings to us as we drove.
The cost was $12 US per hour, so we paid almost $100 for the day, plus tip. It's not at all inexpensive, but was well-suited for our purposes.
This is the first option if you wish to avoid any planning you are likely to do yourself. Also, this isan option if you speak no Russian/English.
Another positive side of this way of going to Pushkin is thatit will avoid you the hassle of having to queue for the possibility of getting the tickets allowing to enter the Palace -- there may be huge ones in summer, and groups usually get their tickets in advance.
The chief drawback is limited time and inability to see what you like and when you like. It's up to you, after all.
By Train : There is a train from Vitebskiy railway station which leaves for Pushkin about every 30 mins.
By Car : From St Petersburg there are taxis or a regular bus (No.287) which travels to Pushkin. It is a bout a 15 minute drive from Pulkovo-1 and Pulkovo-2 airports to Pushkin
Apparently it is possible to rent or take a local cruise on the lake, not sure how far they can take you but well, it depends on what romantic situation you are ;-)