Medical deductions have a 7.5% Adjusted Gross Income (AGI) floor. AGI is the money you got from all sources minus a few "above the line" deductions that I'm not going to get into now. And a "floor" means that you don't get a dollar below that amount as a deduction. Anyways take a look at your AGI and then multiply it by .075 and then take a look at your expenses and see if you have more medical bills than that. Basically unless you have been extremely sick this last year and paid a huge amount out of pocket for medical care it's unlikely that you will have more than this amount and it won't be worth digging through every receipt to find out you just wasted hours of your time on a deduction you won't get a dollar for.
First step is to make sure that the company you are donating to is a charity registered with the IRS. Then you must get and keep receipts, even for small donations. For non-cash contributions it gets more complicated- don't trust those charitable contribution estimators in tax software- the IRS hasn't approved that as a way to estimate the value of your goods and it often over-values items! For clothes and household items you have to know approximately how much you paid for the items, then use an estimated value of what the thrift store would sell them for as a contribution amount. The more detailed of a receipt you can get from the organization the better- pictures and itemized lists of what you are donating help too. Sure you know exactly what you gave away now- but would you remember every item three years from now if the IRS asks you to document it?
Gambling losses are only deductible to the amount of gambling winnings- so don't put a higher amount down even if your losses are higher- you will get audited for that one guaranteed. Losses and gains only average out each year. If you lose money for twenty years and then hitting the big jackpot, those twenty years of losses didn't help you at all. One big reason gambling on the stock market can be more tax friendly than gambling in Vegas, although recently the stock market's odds probably wouldn't beat any casino.
First of all, these are limited by a 2% gross income floor- meaning that you will deduct your expenses by 2% of your gross income before you see the first dollar of deductions. After that point is reached though, the deductions can add up fast. You have to be careful though to not to take too much off or you will have to substantiate it in an audit- probably not something you're looking forward to. It is good to be conservative here, especially when it comes to auto expenses. As a rule of thumb, it starts seeming questionable if employee expenses are more than 10% of your wages from that job.
Realistically, most people just don't spend that much on their jobs, with one big exception: salespeople. If you work in sales you probably have very high employee business expenses and because there is a high likelihood these will trigger an audit you need to stay on top of documenting your expenses. Also it is highly recommended you hire a competent accountant used to working with salespeople to file your returns.
Whatever your occupation, be sure to ask about home office deductions- often you need to have a home office in order to make your auto expenses deductible, otherwise they are considered commuting expenses. Commuting is never considered deductible. A home office has a whole bunch of rules it needs to fit into to qualify- i.e. it can't be the room that you watch TV and hang out with your pals on the weekends, unless that is specifically part of your job.