I tend to take advantage of opportunities to train. Some of the best for me are just before meals, right after the dog's nap and upon returning home after being out for a period of time. I find the dogs are really willing to work at those times. You don't need to do a lot of work at these times just small bits and bites of training. I find these times are great for working on "come" as the dog is excited to see me after an absence or just before their meal time. 

Another way to take advantage of training opportunities is to think of times when you know without a doubt your dog will do something - jump on you, grab something or bark for example. Instead of just waiting for the behaviour to happen, set yourself and the dog up for a mini training session. Think of what you want your dog to do instead in that particular situation and get ready to train it! Try to redirect just before the jump or call away as the dog is walking towards the table to grab something. Then reward the heck out of it so it will be more likely to happen again! 
Change doesn't happen overnight so be prepared to repeat, repeat,repeat. The other trick is to remember it's not beneficial to wait until your dog does something you don't like and then intervene. Try to be pre-emptive - reward and praise when the dog is doing nothing!! Sounds crazy, I know! But think of this - if you only give attention when he is doing something you don't like - that's how he learns to get your attention!