When you are the dealer and a Wizard is turned up you can select the trump suit. (You cannot choose No Trump)
The 2 basic strategies are to either pick your strongest suit (planning to bid high) or your weakest suit (planning to bid low).
The other advantage you have is that you are last to bid so that you can gauge your bid based on the bids made. Generally speaking you will want to take advantage of the fact that you have the right to select trump and consequently will not want to make the bids even unless (a) You have made a very high bid (b) you have a hopeless hand and will be happy simply not to be set. (go down).
It is generally easier to lose tricks so you are more likely to be successful by bidding low. This is particularly effective if you have at least 1 jester and are short-suited.
However if you have high cards and/or need to increase your score dramatically you may opt to bid your strongest and/or longest suit.
Of course there are times when you have a 'square' hand and find that having the choice of trump really does not afford you any real advantage.