If partner opens and I have 7 in a suit, do I go to game?
What do you mean 8 points?  If you have 8 high-card points and 7 diamonds, your hand is probably too strong for a preemptive jump, especially if most of your points are in your long suit.  With a fantastic hand like

&nbsp;&nbsp;&nbsp;&nbsp; ♠ 3 2&nbsp;&nbsp; ♥ 2&nbsp;&nbsp; ♦ A K J 9 7 5 4&nbsp;&nbsp; ♣ 4 3 2

you could easily have 3NT opposite a minimum opening such as

&nbsp;&nbsp;&nbsp;&nbsp; ♠ A 5 4&nbsp;&nbsp; ♥ Q 10 4 3&nbsp;&nbsp; ♦ Q 2&nbsp;&nbsp; ♣ A 7 6 5

With such a nice hand, your main concern should be whether your partner has major suit stoppers.

In a standard american (or 2/1 game forcing) system, you should start by bidding 1♦, and then letting the auction develop.  If your partner rebids 1NT (showing a balanced minimum with stoppers in both majors), you could conceivably raise to 2NT or even 3NT, depending on the type of scoring and your partnership style.

If you have 8 points including distribution, e.g.

&nbsp;&nbsp;&nbsp;&nbsp; ♠ 3 2&nbsp;&nbsp; ♥ 2&nbsp;&nbsp; ♦ A J 9 7 6 5 3&nbsp;&nbsp; ♣ 4 3 2

then a preemptive raise is more reasonable, depending on your partnership agreements.