Actually, if you want to cultivate tuberous Drosera, you should already have some experience with other Drosera, maybe even with winter growing South African Drosera. Therefore you should already have the appropriate material but here again a short overview:
lime-free sand and gravel in grain size 0.5 - 2 mm (0.2 to 0.8")
lime-free or very low lime water
unfertilised white peat with medium degree of decomposition
A light source of a suitable light colour and with sufficient power (if you don't own a greenhouse)
A suitable location where the day temperatures should not exceed 20 °C (68°F) and at night ideally around 10 °C (50°F), but it may be cooler
These tips are for beginners! All this is described on the page Potting in and out in more detail.
If you'd like to start cultivating tuberous Drosera, the first question most people ask themselves is where to get tubers or seeds from. But first the question must be "when will I get tubers or seeds".
I often get inquiries whether I have tubers or seeds and that often in winter when the plants are growing and there are posts in the forum about tuberous Drosera. Unfortunately this is the wrong time because the tubers are growing and nobody would dig up and send the plants during the growth phase. With the seeds in the winter is not usually also so far and would be also the wrong time for sowing. The best time to ask for tubers and seeds and to buy them is in summer.
The best source for tuberous Drosera are the forums. Almost every summer there are offers for tubers and seeds in the forums, rather very rarely in the CPUK forum and practically every summer in the GfP forum. There are often very few offers and you have to hurry. With my offers it is often so that after few days the somewhat rarer tubers are sold out and after one or two weeks mostly the whole remainder also. If in the forum nobody makes offers you can inquire there also times, because some humans perhaps still have a few tubers left however no official offer would like to make.
A second source are commercial traders. Tubers are rarely offered by commercial traders, but seeds are often offered. I don't want to give any recommendations at this point, but if you google, at least for Europe, you will always find a few traders with a good selection (that means more than 3 species!). Normally these traders and of course the forists are very trustworthy and you can be sure that you get what you order and that in a corresponding quality.
You can also very rarely buy tubers and in some cases seeds from Ebay. I haven't done it yet and I won't do it. I don't trust the offers, which for example depict completely different species on the pictures than what are to be sold or if only 3 or 5 seeds are offered for let's to say more than reasonable prices or if the pictures of the plants are colored (e.g. in blue!) to pretend that you can buy something very rare.
It would be quite annoying, if you bought a blue Drosera lowriei on Ebay, which grows up to one meter (3 ft) high, and after 2 - 3 years you notice that this is perhaps a Drosera peltata. OK, actually you can notice this a bit earlier in this special case. I don't want to give the impression that you can't trust Ebay offers in general, but you should be careful what you buy from whom and at what price.
The tuberous Drosera are known to grow in Australia and you can find them on the roadside in ditches, in fields, somewhere where nobody wants to live or in nature reserves. Ordering tubers or seeds directly from Australia is definitely not for beginners, as it is far too expensive. As I said, I will not advertise for anyone here and refer to the CPUK-Forum, where you can read something about this subject. If you know someone in Australia who undermines these scrub every year on their property to plant their carrots or somehow get their hands on seeds or tubers, it would be very nice if you would contact me. Of course these tubers or seeds may not come from nature reserves or similar protected areas.
One of the most important sources for more rare tuberous Drosera is to swap. There are species that are never offered in forums or from commercial sellers and that is the majority of tuberous Drosera species. On the one hand, because these species are practically not cultivated and for this reason no or not enough seeds can be produced and on the other hand, because the propagation of some species bydaughter tubers, leaf cuttings or similar is very diffuicult or unimpossible. The problem, of course, is that you must have something to exchange and if you get something very rare, you should have enough experience to cultivate these plants. These "barter transactions" are usually not handled in public, but rather through personal contacts, which you have to built up over the years and after some years you usually have some interesting species.