Easy, always play someone better than yourself. When I play I set the rating range to be from -25 to +200. When you beat much higher opponents you get more points (up to +10 or + 11) and when you lose you don't lose that many points (-6 or -5). If you can continue to keep up the 50:50 win loss ratio you will gain rating over time.
question about higher play

The vast majority of players win as many as they lose once they're playing opponents of the same ability as themselves. However, if there's a difference in ability then the stronger player is more likely to win and the bigger difference, the greater that likelihood is
oh i see when you are higher ranking you get more points by playing someone who is better than you -- do you lose more points when you play someone below you ???? that only seems fair
that is why the higher you go the faster you advance --- hummmmmmmmm i see now -so i guess this site valves higher rated players more than lower rated players - even though they have the same status --- hummmmmmmmm-- only premuim players should get better deals on ratings they pay for it don't they ? i see now why some players try to fix the games to get more rating points -- and why i ---just once in while-- seem to play a really good player who beats me bad in a as few moves as possible in the 150 rating area - and also why sometimes i win against a clearly better player than me and win at the last minute --hummmmmmmmmm something to think about i guess
when someone like me plays i win one lose two or maybe win two lose one going from 100 to 130 down to 115 back to 150 down to 100 again and again-
question is when one is say 1200 player and player other of equal state -- does he/they/go up a couple of games then down a couple of games -- how does one advance from say 900 to 1200 if you reasonably play well but still there most be ups and downs -- how does one at the higher levels move up ???? you can't at that level win four in row can you ?