Some mix of the following: Buy the biggest one you can afford - Remembering that you have to afford fuel as well.
Try to get a plant that has dual fuel sources Don't buy a coal only plant if 2 other people already have coal fired plants.
Don't get into bidding wars with more experienced players If the above isn't working out, switch tactics - save your money and get the cheapest one
you can this turn and get a better plant next turn.
boardgames.stackexchange.com/users/40/Pat Ludwig
Assuming you're playing with 3 or 4 players, use the 1-2-3-4-5-6-6 strategy.
That is, first power plant should power 1 city, second 2, etc.
Then you'll grow your capacity in a measured pace, and you'll end up with a capacity of exactly 17.
A bad strategy would be: 1-1-3-4-4-5-... because that will make it very hard to reach 17.
Also, by not buying top-of-the-line power plants, you'll probably never be in first place and having to pay most for fuel.
boardgames.stackexchange.com/users/31/Michiel de Mare
Part of it will depend on your long term strategy; buying a low power plant puts you up first for the cheap resources and the prime places on the board.
While more expensive and efficient power plants can give you a leg up in accumulating cash early in the game.
Personally I prefer to start with a relatively inexpensive power plant (as low and cheap as feasible - never more than 2x than the initial value
is my rule of thumb to start out) until I've seen the board locations and then focus on keeping my power plants close to the number of cities I actually own.
With the auction system don't be afraid to let one go if it gets too expensive - the green power plants can be a real bonus if you aren't paying an arm and a leg for them.
boardgames.stackexchange.com/users/65/Chealion
I don't mind to, in the first turn, buying a cheap plant with a lot of storage space (say, three coal).
The cheap plant will help you in the turn order.
Now I stock up on cheap resources (cheap because we are in the start of the game)
so later my one-coal plant can run for 6 turns.
This has the additional bonus that resources become more expensive for the other players.
If you can get a city where you can connect to the next city for free, the money saved allows you to stock up nicely.
boardgames.stackexchange.com/users/387/Konerak
Do not waste your money on plants up to plant number 13, you'll ned to change them soon.
Later ones are better.
And also you don't have many cities at the begining.
Later I'm trying to get plants which could electrify as many cities as possible.
These plants waste a lot of resources, but you will not need to change them until the end of game.
boardgames.stackexchange.com/users/42/Pawka
Four is thought to be one of the best ones to start with.
You'll be assured of going first or second (though I'd avoid three), and you can buy a full boat of coal that will tide you over until turn 3.
boardgames.stackexchange.com/users/96/Lance Roberts
Very hard to say really.
It depends on so many factors.
The best strategy is to have the power plants that use the resources that your competitors do not use.
This then makes the cost of goods cheap to buy, and therefore cheap to fire up.
boardgames.stackexchange.com/users/7/Codemwnci
I've played Power Grid once so far. What is a good beginner's strategy in the initial accumulation of power plants?
Power plants in Power Grid
boardgames.stackexchange.com
<power-grid>
boardgames.stackexchange.com/questions/55
boardgames.stackexchange.com/users/52/wdypdx22
Try to get a plant with dual fuel sources. Don't get into bidding wars with more experienced players. Buying a cheap power plant first and look for plants that use fuel that your competitors don't. Don't get into bidding wars with more experienced players. If you're playing with 3 or 4 players, use the 1-2-3-4-5-6-6 strategy. Try to get a plant that has dual fuel sources  For example don't buy a coal only plant if 2 other people already have coal fired plants. If you buy a low power plant this will place you first for cheap resources and the prime places on the board. One tactic is to start with a relatively inexpensive power plant. Do not waste your money on plants up to plant number 13, you'll need to change them soon. Until you have seen the board locations keep your power plants close to the number of cities you actually own. The best strategy is to have the power plants that use the resources that your competitors do not use.
Try to get a plant that has dual fuel sources  For example don't buy a coal only plant if 2 other people already have coal fired plants.   Don't get into bidding wars with more experienced players. If you're playing with 3 or 4 players, use the 1-2-3-4-5-6-6 strategy. If you buy a low power plant this will place you first for cheap resources and the prime places on the board. S2: One tactic is to start with a relatively inexpensive power plant. Do not waste your money on plants up to plant number 13, you'll need to change them soon. Until you have seen the board locations keep your power plants close to the number of cities you actually own. The best strategy is to have the power plants that use the resources that your competitors do not use.