Yep, the SW advice is to increase HEX's and not syns. MY way is to have a day or two off plan and stick to plan all other days, only because we tend to socialise a fair bit and this works for me!
I've been at target for over a year now and my weight goes up and down according to hormones, eating out, holidays or sticking to plan but this is natural and a part of life - you don't stay at exactly the same weight and this is why SW allow you to go 3 under or 3 over your target weight.
My biggest piece of advice..... keep going to group (assuming you do go!), even if it's not each week, go at least once a month and it will keep you on track.