I think it depends a lot on the type of diet you are trying to follow (ie are you doing calorie counting, WW, SW, low carb etc?) and also the type of person you are e.g. are you a 'I need a reasonable breakfast or I'll pass out' kind of person or a 'take it or leave it' one, a little and often eater or a 1-2 big meals a day person? How are you with carbs, do you find yourself eating big portions or having massive hunger fluctuations if you eat a lot of white bread, pasta etc (different people can react differently?)
In general I am not a breakfast eater and usually just have coffee but I think general healthy eating advice would be to base breakfast around complex carb and protein, so if you need something quick unsweetened greek yoghurt or overnight oats with nuts/seeds and berries is a good one, or if you have time to make a hot breakfast then porridge (again with some fruit and maybe nuts/seeds), or any variety of eggs, or baked beans.
Lunches I try and keep light so home-made veggie soups (bulked out with some beans or pulses and/or with some bread and butter on the side if you need extra oomph at lunch), salads (with a variety of grains and vegetables and a nice dressing, not just boring lettuce and tomato) with a small portion of chicken, pulses or cheese, leftover dinner portions, omlette, or breakfast-y items like eggs, baked beans all good. Maybe some fruit for afters. If you look back through old posts there are quite a lot of good ideas for lunches specifically, some really nice hot 'salad' recipes on here involving roasted veg of various kinds...
Dinners, I try and have a fairly normal 'family' dinner rather than anything specifically 'diet' - just keep an eye on portion size especially carb, and make sure to include plenty of veg. So we have things like chilli, pasta, tray bakes, curry, stir fries, roasts, burgers, sausage and mash - always with at least a couple of portions of veg. I will often take a very small portion of the carb element and extra veg to compensate so I don't have a way smaller plate than everyone else. We always have fruit, sometimes with yoghurt or sometimes just as it comes for afters.
I try and avoid snacking altogether, and alcohol, crisps and sweet things during the week (I will have a moderately sized 'treat' at the weekend). I follow the 5:2 diet so I am sure a lot of the work is done by the fasting not the specific types of food I am eating but the above is fairly balanced and healthy so if you are simply looking to calorie restrict it should work for you, as I say just be careful of your portion sizes as even 'healthy' food can cause you to put on weight if you eat enough of it.
My main tips would be to drink lots of water, try and avoid snacking between meals, have any 'treats' as part of your meal and not as a snack particularly in the evening after dinner (I used to be a fiend for munching biscuits and chocolate in the evenings in front of the telly, that had to be knocked on the head!), use wholemeal bread/rice/pasta instead of white where you can, and eat as much veg as you can (and a couple of portions of fruit as well but don't go mad esp on juices and smoothies as these can be v. sweet). Good luck!