The best method is to begin with study of your own natal chart IMO.
Study your 7th house ruler, the house it is placed in and it's aspects.
If you have any planets in the 7th you will find your partners involving the planets energy. Also it will denote what you are seeking in partners.
Study of Juno by sign and house.
5th house, you should look into as well and use the same methods as with the 7th.
After that, study transits for relationships you have had in the past. So say you had a relationship in 2010 and it began in June. Pull up transits to your natal chart for 2010/june. See what was conjuncting your natal planets or entering a house. For instance it could have been that your 7th house ruler entered your 5th house by transit. And go from there. Then you can move on to composites and synastry charts. There is plenty of info on the internet for both as a good majority are solely interested in relationships/love/marriage concerning astrology.
have fun