What are some guidelines for playing in this situation, or top player
games that give a clear demonstration of possible plans?
It is probably worth starting off by recommending two books.
Understanding Chess Endgames by John Nunn is generally excellent but he has a couple of short sections on B+pawns v N+pawns and BN+pawns v BB+pawns.
Practical Endgame Play - beyond the basics by Glenn Flear is also very good and devotes about 60 pages to minor piece endings where both players have 2 minor pieces along with some pawns.
Bishop v Knight
In the situation you describe with an open center and pawns on both sides of the board a number of things are key:
- King activity - the king is worth 4 pawns in the endgame but works at close range. If your opponent's king is active but yours isn't then you are effectively a piece down
- Knight outpost - with no pawns in the center this is tricky. If the player with the knight can establish the knight on an outpost near the center on the opposite colour to the bishop life will be much easier.
- Pawns on opposite colour to opponent's bishop - if the player with the knight can put all his pawns on squares of the opposite colour to the bishop then the bishop can't attack them and he can play for two results.
2 Bishops v Bishop+Knight
This is very difficult for the side with the knight. Again king activity is very important but the problem for the side with the knight is that the two bishops can combine to harry the king. There are no safe squares. The player with the two bishops, on the other hand, can often waltz his king up the board on the squares of the opposite colour to his opponent's bishop.
Furthermore, no pawn is safe whereas the opponent's pawns can only be attacked by the bishop if they are on the right colour. The side with the knight will likely want to put his pawns on the same colour as his bishop. That way his pawns will be much easier to defend and there will be much less to fear from a trade of one pair of minor pieces. Again, try and establish an outpost for the knight.
In both cases the side with the extra bishop wants to use that advantage to attack the opponent's pawns.
Just as important as, if not even more important than, knowing what plans you want to try and execute is knowing what the plans are for your opponent. Often the route to victory lies in first thwarting your opponent's plans.